International Organization Foundation - … International Organization The Formation and Fulfillment of Alliance Agreements History is full of examples of cases in which state leaders

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Alliance Reliability in Times of War: Explaining State Decisions to Violate TreatiesAuthor(s): Brett Ashley LeedsSource: International Organization, Vol. 57, No. 4 (Autumn, 2003), pp. 801-827Published by: Cambridge University Press on behalf of the International Organization FoundationStable URL: http://www.jstor.org/stable/3594847 .Accessed: 24/05/2011 15:01

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Alliance Reliability in Times of War: Explaining State Decisions to Violate Treaties Brett Ashley Leeds

Abstract Understanding the conditions under which state leaders are willing to honor alliance commitments in war will increase knowledge about the escalation and diffusion of conflict and about the propensity of states to fulfill agreements under anarchy. New data analysis provides evidence that alliance commitments are fulfilled about 75 percent of the time. But how can one understand the failure of alliance partners to act as promised in the remaining 25 percent of cases? Formal modelers have deduced that because of the costs associated with alliances, state leaders who form alliances are likely to fulfill them; those alliances that are formed should be fairly reliable. I argue, therefore, that one can best account for violations of alliance agreements either through an understanding of the factors that reduce the costs of violation or through changes that have occurred since the alliance was formed. Using detailed data on alliance commitments between 1816 and 1944, I find evidence commensurate with this argument. Changes in the power of states or in their policymaking processes are powerful predictors of the failure to honor past commitments; and nondemocratic states and major powers, sets of states that I argue suffer lower costs from reneging on agreements, are more likely to violate treaties.

The Reliability of Allies in War

Traditional theorizing in international relations has suggested that in a state- centric world order in which national leaders retain ultimate authority, reliance on

Previous versions of this article were presented at the annual meeting of the Midwest Political Sci- ence Association, April 25-28, 2002, Chicago, Illinois; the annual meeting of the International Studies Association, March 24-27, 2002, New Orleans, Louisiana; and the annual meeting of the American Political Science Association, August 31-September 3, 2000, Washington, D.C. This research was supported by the National Science Foundation (grant SES-0095983) and the Committee on Faculty Re- search Support at Florida State University. The author would like to thank Matt Baum, Chris Butler, David Davis, Erik Gartzke, Kristian Gleditsch, Andrew Kydd, David Lake, Andrew Long, Lanny Mar- tin, Lisa Martin, Sara Mitchell, Will Moore, Cliff Morgan, Glenn Palmer, Dan Reiter, Jeff Ritter, Mitch Sanders, Randy Stevenson, Ric Stoll, and Suzanne Werner for helpful advice on this research. Data for replication can be obtained at (www.ruf.rice.edu/-leeds).

International Organization 57, Fall 2003, pp. 801-827 @ 2003 by The IO Foundation. DOI: 10.1017/S0020818303574057

802 International Organization

promises can be dangerous. Because there is no governing authority to manage and enforce relations among states, agreements among states are particularly prone to opportunistic behavior. Some scholars have gone so far as to argue that promises made without enforcement have no independent force; treaties are mere "scraps of paper" that will be violated if state interests change.' In the realm of military security, where honoring past commitments involves significant costs and risks, treaties should be particularly vulnerable to violation.2

Recent theorizing, however, has called this view into question. Several scholars have wondered why, if international agreements are useless, do state leaders in- vest so much time and effort in negotiating and designing them? Despite the warn- ings of some political scientists, state leaders continue to form and appeal to military alliances, and some leaders make alliances a significant part of their security policy. This recognition has caused a number of scholars to reevaluate the role of formal international agreements for security cooperation.

Morrow, Smith, and Fearon view military alliances as a means by which state leaders can provide credible signals of their future intentions.3 These theorists deduce that because of the costs that are associated with alliances, only states that are fairly likely to fulfill their alliance obligations are likely to form them; bluffing should be rare. As a result, alliances serve as reliable indicators of the behavior of the state should war occur. Lake and Conybeare, on the other hand, view alliances as a means of enhancing security through the exploitation of joint production economies.4 Lake notes, however, that the specialization and coordination necessary to produce joint gains will only be possible when leaders feel confident about the reliability of their partners; alliance relationships will develop when fears of opportunism have been overcome. These arguments are similar to the broader theories of cooperation presented by Downs, Rocke, and Barsoom; Fearon; and Leeds-all of which predict that leaders are most likely to form cooperative agreements that they believe are self-enforcing, implying that the cooperative agreements that one observes should exhibit a high degree of compliance.5

Whether one views formal alliances as primarily serving as costly signals of intentions or as mechanisms for coordinating economies of scale in security production, dominant theories predict that alliances should be effective instruments of policy and that state leaders are likely to fulfill the alliance commitments they make most of the time. Recent empirical evidence seems to support these claims. While studies by Sabrosky and by Siverson and King report that state leaders assist their allies in war in approximately 25 percent of cases, a recent study by

1. In a famous quotation, German Chancellor Theobald von Bethmann-Hollweg reportedly referred to the guarantee of Belgian neutrality as "a scrap of paper" when preparing to invade in August 1914. See Cooke and Stickney 1931, 382.

2. For example, Mearsheimer 1995. 3. See Morrow 1994; Smith 1995 and 1998a; and Fearon 1997. 4. See Lake 1996 and 1999; and Conybeare 1992 and 1994. 5. See Downs, Rocke, and Barsoom 1996; Fearon 1998; and Leeds 1999.

Alliance Reliability in Times of War 803

Leeds, Long, and Mitchell reevaluates this question using new, more detailed data and an improved operationalization of the concept of reliability.6 Leeds, Long, and Mitchell report that when the conditions invoking alliance commitments arise, state leaders fulfill their commitments in 74.5 percent of cases.

Yet, states abrogate 25 percent of their alliance commitments when war occurs. What accounts for the fact that states honor some commitments but not others? Were these alliances formed as bluffs by leaders who gambled that they could deter aggression and avoid fulfilling their commitments? If so, can one identify likely "bluffers"? Did leaders recognize the possibility that these alliances were vulnerable to violation when they formed them? Or were these agreements formed under conditions in which leaders believed they would be reliable, but new conditions created different incentives? Alliances are neither always violated nor always fulfilled. The goal of this article is to elucidate factors that increase the probability that leaders will fail to comply with treaty commitments.

In this article, I investigate the conditions under which leaders are most likely to violate their alliance commitments in the face of war. I argue that alliance commitments are most vulnerable to violation when either the costs a leader expects to incur from formation and violation are comparatively low (conditions that encourage bluffing and risk taking), or when significant factors have changed between the time the alliance was formed and invoked, causing leaders to reevaluate their interests. Analyzing the population of alliances and wars during the period 1816-1944, I find statistical support linking nondemocratic states and major powers, two groups of states for whom the costs of reneging on agreements may be comparatively low, with a tendency to violate alliance commitments. The strongest evidence, however, supports the claim that dynamic factors predict alliance violation. Variables representing changes in the power of a state and changes in the domestic policymaking processes of a state are the best predictors of the failure to fulfill alliance commitments. It seems possible as well that challengers may use these factors to assess the reliability of alliances. Targets with allies whose commitments are questionable may be vulnerable to attack.

This study helps to illuminate both the promise and the difficulty involved in international cooperation. On the promise side, the high probability of alliance fulfillment suggests that one can be optimistic about contractual efficacy in the international system. State leaders can design agreements that they have incentives to fulfill, and alliance treaties can be a useful tool in international politics. Most alliances are formed by sincerely committed states. At the same time, rely- ing heavily on the commitments of others can be dangerous. Under some conditions leaders are willing to bluff and accept risky commitments, and state leaders are sometimes willing to break contracts when past agreements do not suit present interests.

6. See Sabrosky 1980; Siverson and King 1980; and Leeds, Long, and Mitchell 2000.


The Formation and Fulfillment of Alliance Agreements

History is full of examples of cases in which state leaders considered forming alliance agreements but chose not to because they recognized that they or their partners might be unwilling to fulfill their promises should conflict arise. In the 1920s and most of the 1930s, for instance, Great Britain was repeatedly ap- proached by France and the Soviet Union about forming an anti-German alliance with Germany's eastern neighbors, particularly Czechoslovakia. Despite the fact that the British government had a definite interest in deterring German aggression in the East as well as the West, the British leaders refused to sign any Eastern pacts. They knew that they were unwilling to endure the costs of fighting Ger- many over Czechoslovakia, and this proved to be the case in 1938.7

After the breakdown of the Munich agreement and the Nazi invasion of Czecho- slovakia, when it became clear that Adolf Hitler's appetite for expansion had not been satiated, protracted negotiations took place over several months among Great Britain, France, and the Soviet Union regarding an anti-German alliance for joint defense of the remaining eastern states. While all three powers had shared interests in deterring (and if necessary defeating) Hitler, their negotiations failed and

they did not form a joint anti-German front. Soviet leaders expressed serious doubts about the willingness of the western powers, and especially Britain, to fulfill the commitment were Hitler to attack, and British and French leaders were uncertain that the Soviets would protect smaller states in Eastern Europe.8 Because of their joint distrust, Hitler's eastern and western enemies were unable to reach an agreement, and instead, the Soviet Union agreed to an independent nonaggression pact with Germany in which the two powers agreed to divide Poland and the Soviets promised to remain neutral should Germany decide to attack in the West.9

Why did Hitler's enemies avoid these commitments? Why were these states so reluctant to form agreements that might go unfulfilled? In forming military alliances, state leaders consider the actions that will be required in the event the alliance is invoked. If it is unlikely that their partners will fulfill the agreement or if the state leaders believe they may not be willing to fulfill the commitment themselves, they may expect to endure costs but gain limited advantage from the treaty. This becomes more apparent when one considers the motivations of states to commit to alliances.1'

7. See, for example, Ross 1983, 58, 62, 101; Parker 1969, 307; and Gantenbein 1975, 367. 8. See Adamthwaite 1977, 207-8, 218-19; and Parker 1969, 326-29. 9. Grenville 1987, 195-96.

10. I distinguish here between alliances, which are "written agreements, signed by official represen- tatives of at least two independent states, that include promises to aid a partner in the event of military conflict, to remain neutral in the event of conflict, to refrain from military conflict with one another, or to consult/cooperate in the event of international crises that create a potential for military conflict" (Leeds et al. 2002, 238), and alignments, which are "expectations of states about whether they will be


There are two primary reasons for state leaders to commit to formal alliances." First, alliances can serve as signals of intention, providing information that allies hope will deter enemies from challenging them or compel enemies to accede to their demands. Second, the institutionalized security cooperation that may be associated with alliances may produce economies of scale in the provision of defense, allowing individual states to reduce their defense burdens, and may also improve the war fighting ability of a coalition. I will discuss each of these advantages in turn.

One main purpose of creating formal alliance agreements is to provide information to both allies and adversaries regarding a state's intentions. State leaders hope that making their commitments to their allies clear will discourage potential adversaries from attacking their coalition in recognition of its strength, or that it will compel adversaries to comply with coalition demands rather than risking war. Thus, a main purpose of alliances is to prevent war through increased ability to deter conflict. 12

Why does facing an alliance influence the decisions of potential adversaries? Because there are costs associated with alliances at formation and/or at invocation, under most conditions only leaders who believe they will have incentive to fulfill their alliance commitments are likely to form alliances.13 At formation, leaders incur the costs of negotiating and instituting the agreement. Throughout the duration of the alliance leaders incur the costs of policy coordination and the corresponding loss of autonomy. At invocation, the leaders must either accept the costs of fulfilling their commitment, which may involve active fighting, or the costs of reneging on a commitment, which can have negative reputational effects and can cause domestic and international audiences to question not only the leaders' reliability, but also their competence.14 Because alliances are costly, potential adversaries can expect that most states that form alliances are sincerely committed to fulfilling their commitments.

The ability to influence the beliefs and behavior of an adversary, however, may create a temptation for leaders to bluff. Leaders might choose to form alliances

supported or opposed by other states in future interactions" (Snyder 1997, 6). An alliance is a formal contract specifying obligations to which more than one state expressly accedes, while an alignment is an informal coalition.

11. I limit myself to discussing the international security benefits derived from alliances. Some scholars have argued that leaders may form alliances for reasons other than to enhance their security. For instance, more powerful states may offer security alliances to less powerful states in return for influence over the domestic and/or foreign policies of their weaker partners (for example, Schroeder 1976; and Morrow 1991). Less powerful states may agree to join a coalition to obtain economic or military aid. While these arguments suggest that not all alliance members are motivated by the security benefits of alliances, each theory also suggests that at least one alliance member is motivated by the security benefits. These arguments can best be thought of as specific cases of issue linkage-the security benefits of alliances are linked with other issues to create bargains that are attractive to all potential members. Thus, these deals depend at least in part on the security motivations discussed here.

12. See Morrow 1994; and Smith 1995 and 1998a. 13. See Morrow 1994; Fearon 1997; and Smith 1998a. 14. See Morrow 1994; Smith 1995, 1998a,b; and Fearon 1994 and 1997.


that they may not fulfill in the hope of deterring potential challengers and avoiding conflict altogether. Under what conditions are leaders likely to take this gam- ble? If bluffing does occur, it should only happen when (1) the costs of forming the alliance are relatively low, and (2) the costs of breaking the alliance commitment if the ally is attacked are viewed as low (in comparison to the expected deterrent benefit). If forming an alliance requires a large initial investment, for instance to establish and staff new bases and coordinate military activities, states that are not sincerely committed are less likely to form alliances. The sunk costs of alliance formation and maintenance create a screening process that deters bluffing. Thus, states that are insincere are more likely to form alliances that do not require a large initial investment. Second, leaders will weigh the benefits to be gained from the bluff against the costs that will be incurred if the bluff is called. When leaders expect to experience high costs from reneging on an agreement and are unwilling to fulfill the commitment should conflict arise, it is less likely that they will take the chance of bluffing.

Thus, low-cost alliances and comparatively low costs of reneging on agreements should encourage bluffing. The same factors, however, should reduce the credibility of the alliance in the eyes of adversaries. Deterrence and compellence depend crucially on the credibility of the joint threat. Alliances will only be successful at changing the behavior of adversaries if adversaries believe that allies will fulfill their commitments. Factors that decrease the costs of alliance formation and/or reneging on a past commitment should increase the incentive to bluff and the corresponding probability that an alliance commitment will be violated. These same factors, however, should decrease the probability that the alliance deters challengers and thus decrease the value of the alliance to members.'5

Morrow, Smith, and Fearon have modeled these strategic interactions.'6 Their models lead them to conclude that there is only a small range of parameter values for which bluffing is an equilibrium strategy.'7 They conclude that most of the

15. There is a potential tradeoff, however. Costly alliances should improve deterrence and reliability, but they may also introduce the potential for entrapment. States that feel assured of allied support may engage in more aggressive and risky foreign policies, exposing allies to an increased risk of un- wanted war. See, for example, Snyder 1984 and 1997. Fearon 1997 suggests that this moral hazard sometimes leads states to send "half-hearted signals." It is also possible, however, that states may control moral hazard by specifying clearly the conditions under which an alliance may and may not be invoked. For instance, many alliances specify that partners will provide defensive support only if the ally is attacked without provocation, and/or that an alliance is only relevant when an ally is attacked and not when any member of the alliance initiates conflict against another state. See Leeds 2003.

16. See Morrow 1994; Smith 1995 and 1998a; and Fearon 1997. 17. More specifically, Fearon 1997 and Smith 1995 deduce from their models that all alliances should

be reliable; there are no equilibria in which insincere states form alliances. Both authors suggest that aspects of international politics that were not included in their models may account for observed violations. Smith's model assumes complete and perfect information. With incomplete information, bluffing might be an equilibrium strategy under some circumstances, but he is doubtful that this accounts for all observed violations. See Smith 1995, 418. Smith 1998a allows for incomplete information. Of the seven types of equilibria in the model, only one (E3) supports bluffing. See Smith 1998a, 329-32. Morrow 1994 finds two semi-separating equilibria in which some states that will not intervene should


time, alliances should be reliable, and bluffing should be rare. Yet, none of these studies includes any empirical assessment of how often real-world events fall into the range of parameters that encourage bluffing. Should one expect bluffing to occur 2 percent of the time, 12 percent of the time, or 20 percent of the time? One of the purposes of this study is to assess whether most of the alliances that are violated when conflict occurs were probably bluffs that were called. This will help one to judge the prevalence of bluffing. Perhaps the 25 percent of alliance commitments that are violated when war occurs represent the percentage of cases for which bluffing is in equilibrium and the bluff fails to deter conflict. On the other hand, if another explanation for alliance violation seems to account systematically for the decisions of states to violate their past commitments, one can assume that the observed commitment violations are not all gambles gone bad.

While one reason leaders choose to form military alliances is to influence the behavior of adversaries, a second motivation for forming alliances with other states is the attraction of economies of scale and the benefits of coordination in the provision of security. If state leaders can count on assistance from allies in the event of war, each state can transfer some portion of individual defense spending to other purposes, for instance, welfare spending or promotion of economic growth. By maintaining smaller individual forces and/or joint research and arms programs, states can free some portion of their defense budgets for other uses. 1 Lead- ers may also believe that coordination will result in a stronger and more successful combined force should war occur. If a coalition coordinates military activities and plans ahead for joint action, the strategic benefits of capability aggregation can be maximized. States may have complementary comparative advantages; sea power and land power, for instance, can be integrated to enhance joint security. With coordination, the joint forces are likely to be a more formidable adversary than they would absent joint planning.'9

When the commitment of allies is questionable, however, joint production of arms, integrated forces, defense specialization, and reduction of individual defense burdens are likely to be deemed too risky. Economies of scale in the provision of defense are unlikely to arise in the absence of considerable confidence and trust. Basing one's security policy on reliance on others requires great faith that the commitment of one's allies is secure.20 Thus, Lake argues that leaders will only attempt to exploit potential joint economies in security production when they have satisfied themselves that the risks of opportunism are sufficiently low.21 If

war occur form alliances to influence the beliefs of an adversary in the hope of deterring conflict. There are also separating and pooling equilibria in the model, however; and Morrow notes that without knowing the distribution of values of parameters in the model, one can not know the frequency with which each equilibrium holds in the real world. See Morrow 1994, 293.

18. See Lake 1999; and Conybeare 1994. 19. Morrow 1994. 20. McGinnis 1990. 21. Lake 1999.


the threat of opportunism is significant and cannot be ameliorated at reasonable cost, leaders will prefer to forego potential mutual gains and will maintain unilateral defense strategies.

When the benefits of cooperation are quite high, however, leaders may be willing to take greater risks and accept alliances that pose a high risk of violation. Lake claims that it is hard to assess whether many real-world cases fall into this risk-taking range because the key concepts in his theory are difficult to measure. He seems skeptical that many fall into this range, however, because the benefits of alliances are partially endogenous.22 Because leaders will avoid investment in specific assets when fears of opportunism have not been overcome, it is unlikely that alliances that produce high benefits will emerge without highly credible commitments. Alliances that produce greater benefits also come with higher governance costs and require more credible commitment on behalf of the allies.

Creating self-enforcing agreements is facilitated by the latitude that state leaders have in designing their alliance agreements. When questions of credibility exist, leaders may be able to find ways to increase the value of the alliance and improve their incentives to collaborate with their alliance partners in wartime through provisions that make the alliance more reliable. Alliance agreements may include provisions for one state to station troops on the territory of another, for integrated command of military forces, or for joint military planning. Such means of institutionalizing cooperation are designed to increase the benefits of the alliance by improving the chances that it will be honored and the likelihood that it will be effective at advancing the goals of the members. Alliances can change the incentives of state leaders to participate in conflicts on behalf of their allies, and when necessary, state leaders may turn to provisions for institutionalizing military collaboration to increase the credibility of their joint commitment.23

Not only are leaders careful in selecting the agreements that they are willing to make and in designing their agreements to promote fulfillment, but they are careful in crafting the language of the treaties as well. Most treaties contain specific language regarding the conditions under which the alliance comes into effect and the actions that the members are required to take under these conditions. Alliances are often not blanket promises to assist one another in any military conflict, but rather alliances specify the conditions under which the ally will and will not be willing to offer aid and the extent of aid that will be provided. Leaders limit their promises to the instances in which they expect to be willing to intervene on behalf of their allies and make clear the actions they expect their allies to provide in the event the alliance comes into effect.24

State leaders recognize the difficulties of cooperating under anarchy and are careful to form alliances that are specific and credible. Under most conditions,

22. Ibid. 23. See Lake 1996 and 1999; and Leeds 2000. 24. Leeds, Long, and Mitchell 2000.


leaders are reluctant to make promises that they or their partners are unlikely to uphold. This care in the design of alliance treaties should result in few violated commitments. Research by Leeds, Long, and Mitchell supports this expectation. In their study of alliance performance in war from 1816-1944, Leeds, Long, and Mitchell find that in 74.5 percent of cases, allies fulfill the specific promises they have made.25

Why Do Violations Occur?

Despite the fact that Leeds, Long, and Mitchell find evidence that the great major- ity of alliances are fulfilled when war occurs, their study does not answer a major question. If leaders are so careful to form agreements that they expect to be fulfilled, then how can one explain the fact that in approximately 25 percent of cases in which alliances are invoked by war, allies fail to uphold their commitments? Is this the proportion of real-world cases that fall into the narrow ranges associated with bluffing and risk taking? If so, can theories of alliance formation help one to anticipate which alliances will be fulfilled and which will be violated? Or is there some other factor consistent with these theories that explains these violations?

One possibility is that a selection effect produces a biased observed sample. Smith has argued that opportunities to prove a state's reliability in war are more likely to emerge for questionable alliances than for secure ones. Because challenging states choose conflicts they can win, they are more likely to target states whose allies they expect will not fulfill their commitments.26 Thus, challengers are more likely to start wars and test the commitments of allies when they think those commitments are most questionable. This would suggest that while 25 percent of opportunities for allies to prove their reliability in war result in alliances not being honored, one cannot generalize from this sample to those alliances that were not invoked by war. Instead, one should expect the sample of alliances that successfully deter conflict to be more reliable than those that did not succeed at deterring enemies.

This argument, while certainly a possible explanation, suggests, first, that a class of unreliable alliances exists and, second, that challengers can identify reliable and unreliable alliances with reasonable success. One must explain how outsiders consistently identify alliance promises that will go unfulfilled. Thus, for this argument to hold, one must be able to identify something observable that distinguishes alliances that may not be successful from those that most likely will be. I argue that there are at least two possible avenues that would account both for the exis- tence of a pool of risky alliances and the ability of challengers to identify questionable commitments.

25. Ibid. 26. See Smith 1995, 1996, and 1998a. See also Gartner and Siverson 1996.


First, it may be the case that all state leaders are not equally sensitive to the risks of nonfulfillment. Leaders of states who expect low costs from reneging on an alliance commitment are more likely to bluff, because the risk of reneging if deterrence fails is more likely to be balanced by the possibility that the bluff is not called. Similarly, leaders who can adjust their policies quickly and easily are more likely to be willing to take risks on policies that may be unsuccessful and will have to be changed quickly. If one can identify observable characteristics that are associated with the willingness to form alliances that will go unfulfilled, these factors should also be associated with a higher rate of alliance violation.

Second, members of alliances could experience changes that affect their willingness to fulfill past commitments.27 Under this scenario, an alliance might be credible to members and to challengers when it is signed, but it may become less desirable as changes in the members and/or environment occur. Sometimes, dra- matic change will cause state leaders to terminate their alliance commitments. For example, Siverson and Starr find evidence that regime change within states is associated with alliance changes; Bennett reports that the termination of wars, changes in power, and changes in security are associated with shorter alliance durations; and Morrow finds that changes in power are associated with the termination of alliance commitments.28 The legal doctrine of rebus sic stantibus (as matters stand) has often been used to justify the unilateral termination of agreements when a major change in relevant circumstances occurs.29

At the same time, institutions and treaty commitments may continue to exist even as they become less desirable, because of sunk costs and inertia.30 Only when the conditions invoking past promises arise might the leaders determine that they are unwilling to adhere to promises made when circumstances were different. If environmental and policy changes are visible to challengers, challengers may choose to target these alliances in recognition of their vulnerability. Again, this condition could explain both why alliances that prove unreliable exist and why challengers can identify them successfully.

In order to determine whether changes in relevant conditions between alliance formation and invocation and/or features systematically associated with lower costs to abrogation and more willingness to bluff can explain the decisions of some state leaders to violate their alliance commitments when war occurs, I analyze a statistical model of the probability of alliance commitment violation. I examine the relationships between the probability of alliance violation and factors associated with the alliance members and changes since the alliance was signed. I also investigate whether the original targets of wars are particularly vulnerable to abandonment by their allies to see if challengers are targeting states with questionable

27. Smith 1995. 28. See Siverson and Starr 1994; Bennett 1997; and Morrow 1991. 29. Kegley and Raymond 1990, 90. 30. Keohane 1984.


alliance commitments. The research design and specific hypotheses are described below.

Research Design and Hypotheses

I use data on alliance reliability during war created by Leeds, Long, and Mitchell to analyze the probability of alliance commitment violation.31 Using the Alliance Treaty Obligations and Provisions (ATOP) data set,32 Leeds, Long, and Mitchell determine the instances in which alliance commitments are invoked by a given war and then code each alliance as honored or violated in that conflict based on whether the leaders took the actions they had promised to take in their treaties.33 The authors find that of 110 cases in which alliances were invoked by war between 1816 and 1944, alliance commitments were honored in eighty-two instances, or 74.5 percent of the cases.34

In the Leeds, Long, and Mitchell study, each alliance is judged as an individual entity. If any alliance member violates the alliance, the entire alliance is considered violated; only if no member is in violation is the alliance honored. Because the argument of this article involves evaluating the decisions of individual states to honor or violate their commitments, I include each member's decision as an individual case. Thus, for each war, I determine which alliance member or members were in a position to choose whether to honor the alliance. For instance, when Poland was attacked by Germany in World War II, both Great Britain and France decided to honor their alliance with Poland. When Austria-Hungary attacked Ser- bia at the beginning of World War I, Germany honored the Triple Alliance, whereas Italy did not. Neither Poland in World War II nor Austria-Hungary in World War I, however, decided whether to honor their alliances. Their participation in the two conflicts created the war performance opportunities for these two alliances. Thus, I consider Britain's decision to support Poland, France's decision to support Po- land, Germany's decision to support Austria-Hungary, and Italy's decision to violate the commitment to Austria-Hungary as cases for analysis.

31. Leeds, Long, and Mitchell 2000. 32. Leeds et al. 2002. 33. The ATOP data set and the reliability coding of Leeds, Long, and Mitchell 2000 are available at

(www.ruf.rice.edu/-Leeds/atop.html). 34. The temporal sample is dictated by the fact that ATOP data has only been collected for the

period 1816-1944. It is the detailed information about alliance obligations included in the ATOP data set that makes it possible for Leeds, Long, and Mitchell to evaluate which wars invoked particular alliance commitments and what actions the members were required to take in that conflict. This information allows them to judge whether the specific promises embodied in the treaties were honored or violated in war. It is important to note that the Leeds, Long, and Mitchell operationalization of reliability is significantly different than that employed in earlier studies (for instance, Sabrosky 1980; and Siverson and King 1980). While previous studies examined the rate at which allies fight together in wars regardless of the provisions of the alliance treaty, Leeds, Long, and Mitchell attempt to judge whether allies lived up to the actual promises they made.


In most instances, the first member of the alliance to enter a war creates the opportunity and other members decide whether to honor or violate their commitments. I did, however, consult historical sources on each case to be certain that the coding of decision makers has face validity. In a small number of cases, I could not differentiate between alliance members; the decisions to fight together seem to be made simultaneously. In these few instances, I chose the decision- making member of the dyad by random draw.

I limit my analysis of alliance reliability to alliances that have provisions for defensive or offensive cooperation or for neutrality in the event of conflict. Some alliances only commit leaders to refrain from conflict with one another or to consult in the event of international crises. Because these agreements do not require active behavior during war, it is not possible to judge their reliability through an evaluation of war performance. The motivations for alliance formation that I have discussed (signaling and coordination) are also most directly relevant to alliances that prescribe and proscribe specific activities in the event of conflict.35

My set of cases, therefore, includes 143 individual state decisions to honor or violate alliances during wars.36 Of these, 115 (80.4 percent) are honored. The dependent variable is a dummy variable labeled 1 if the alliance commitment is violated and 0 if the alliance promise is fulfilled. The method of analysis is logit with robust standard errors.

I test three categories of independent variables in my attempt to explain the conditions under which state leaders violate their alliance commitments. I consider characteristics of the alliance member that may be associated with lower

35. Defensive, offensive, and neutrality commitments all have the potential to provide information to allies and adversaries regarding likely behavior should conflict occur. While the theories of Morrow 1994 and Smith 1998a are specifically aimed at explaining defense pacts, Smith 1995 discusses offense pacts in a similar manner. Moul 1988 argues that a primary purpose of neutrality pacts is to assure others of future intentions. Neutrality pacts can deter attacks on partners if adversaries previously believed that a state might fight against the target in a war, but such pacts can also encourage attacks on outsiders if allies previously feared that a state would aid its intended target. Thus, neutrality pacts can share signaling characteristics with either defense or offense pacts in different circumstances. See also Leeds 2003. States committing to defense pacts and offense pacts have the potential to benefit from the economies of scale associated with joint security economies. Neutrality pacts sometimes also involve coordination. When states promise "benevolent neutrality," they often promise to thwart the efforts of enemies to use their territory and resources in the conflict. While states do not promise to enter the conflict, they do promise to protect their neutrality, which may require active effort. Portugal's neutrality commitment to Britain in World War II, for instance, included promises to provide British access to Portuguese ports and airfields and to defend these facilities. See Great Brit- ain Foreign Office various years, vol. 146, 447-51.

36. Each state's decision to honor or to violate an alliance during a given war is considered an independent case. It is possible, however, and perhaps likely, that the decisions of multiple alliance members to fulfill a single alliance are not independent. It is also occasionally true that the same alliance is relevant to more than one conflict. Decisions to honor or violate an alliance in one war may not be independent from the decision to fulfill that same alliance in another war. Because I recognize the possibility that these observations are not independent, I designate observations associated with the same alliance as members of a single group and assume that observations are independent across groups, but not necessarily within groups. This relaxation of the assumption of independence affects the estimated standard errors, but not the estimated coefficients. See Rogers 1993.


costs of nonfulfillment, changes affecting the decision-making state since the alliance was formed, and the ally's role in the conflict.37

Characteristics of the Alliance Member

I test two characteristics of the decision-making state: domestic political structure and power status in the international system. Several scholars have argued that leaders of democratic states are particularly sensitive to the costs of breaking commitments and are thus more likely to uphold their promises.38 Their sensitivity to failed policies may make democracies particularly reluctant to bluff or to form risky agreements.39 This conclusion can be derived from two different features of democratic states-the accountability of leaders to a broad constituency and the lack of policy flexibility available to leaders working under strong institutional constraints.

Because democratic leaders are accountable for their actions to a large segment of the population and can be replaced at regular intervals at fairly low cost, they tend to be particularly concerned with providing good public policy and proving their competence to their constituents.40 Several scholars have argued that policy vacillation and called bluffs lead people to question their leader's competence.41 Also, because leaders operating in democratic political systems must share power with others in the policymaking process, these leaders tend to find it more difficult to shift policy rapidly. As a result, their commitments to fulfill their promises may be more credible, but they may also be very wary of making deals that will be unsuccessful, because changing policy to account for new realities may be challenging.42 If democratic leaders find reneging on agreements particularly costly and risky commitments particularly undesirable, nondemocratic states may accept riskier commitments and in turn may violate alliances more frequently.

The costs associated with abandoning an ally may also differ depending on the power of a state. Major powers may have more to lose reputationally for failing to support an ally, because they tend to have more numerous and extensive international commitments than minor powers.43 If reneging on one treaty calls others into question, major powers might be wary of the ancillary costs to abrogation. At the same time, major powers also have more latitude in their foreign policy decision making.44 A minor power may fear retribution from stronger states for failing

37. I used the EUGene computer program to assemble some of the independent variables for analysis. See Bennett and Stam 2000.

38. See Fearon 1994; Gaubatz 1996; Leeds 1999; and McGillivray and Smith 2000. 39. See Fearon 1994; and Leeds 1999. 40. See, for example, Bueno de Mesquita et al. 1999; and Smith 1998b. 41. See Przeworski 1991; Fearon 1994; and Smith 1998b. 42. See, for example, Morgan and Campbell 1991; Leeds 1999; and Martin 2000. 43. In the ATOP data set, major powers average 2.77 alliances per year, while minor powers aver-

age 0.48 alliances per year. This difference in means is statistically significant at the .0001 level. 44. Morgan and Campbell 1991.


to fulfill a commitment and may be unwilling or unable to resist pressure from other powers to fulfill obligations. When Iraq and Iran resisted honoring their commitments for use of their territory to Great Britain and the Soviet Union during World War II, British and Soviet leaders used force to attain compliance.45 Minor powers are also more likely to be highly dependent on alliances for security provision and thus unwilling to risk the termination of an alliance because of nonfulfillment.

The effect of allied assistance on conflict outcome is also likely to vary systematically between major and minor powers. All else equal, stronger states should have more impact on the outcome of a conflict. The models developed by Smith and Morrow suggest that allies with a greater probability of winning the war are more likely to intervene.46 If the leader of a minor power knows that he or she would be joining a losing effort, avoiding the conflict might be particularly ap- pealing. By this logic, it is not surprising that the Little Entente, an alliance formed by Czechoslovakia, Yugoslavia, and Romania after World War I to defend each other in light of Hungarian revisionism, proved impotent when Germany and Russia emerged as bigger threats. In most instances, however, small states will avoid committing themselves to treaties that would require them to join conflicts that their coalition has little chance of winning. Instead, they will design treaties that specify the circumstances under which they will and will not aid their partners. Thus, they should not often find themselves in the position to renege because of the futility of the effort; that eventuality would have been anticipated earlier.47

Previous studies have been inconsistent in their findings regarding the relationship between power status and alliance violation: Krause and Singer find that major powers are less likely to join their allies in war; Bolks finds no relationship between power status and the probability of fulfilling an alliance commitment; and Sabrosky finds that alliances between major and minor powers are most vulnerable to violation, whereas major-major and minor-minor alliances are indistin- guishable.48 Because I link the probability of violation to the costs associated with reneging, the most relevant question is whether on average, major powers or mi- nor powers suffer greater costs from breaking past commitments. Because minor powers are more dependent on continuing alliances for security and are more likely to suffer material punishment for failing to fulfill alliance obligations, the costs of reneging should be particularly high for minor powers.

45. Langsam 1943, 801-2. 46. See Smith 1995 and 1998a; and Morrow 1994. 47. The Little Entente is an excellent example. The alliance specified that the members were obli-

gated to assist a partner only if threatened by Hungary or Bulgaria. League of Nations various years, vol. 6, 211, 217, and vol. 54, 259. Because Germany and Russia were certainly viewed as the most threatening states to the signatories at the time the alliance was formed, it is telling that these states were excluded from the casus foederis.

48. See Krause and Singer 1997; Bolks 1998; and Sabrosky 1980.


To summarize, I test two hypotheses linking characteristics of states and their propensities to violate alliances. Both hypotheses are motivated by the fact that states with different characteristics may have different degrees of sensitivity to the costs of broken commitments. If this is true, some states may be more willing to form alliances and later abandon them; thus, one may witness more violated alliances among states with these characteristics. In other words, these may be the states that are tempted to bluff and/or to accept treaties with a greater risk of abrogation.

H1: Nondemocratic states are more likely to violate alliance commitments during war than democratic states.

H2: Major powers are more likely to violate alliance commitments during war than minor powers.

I evaluate the first hypothesis by including a dummy variable in my analysis that is coded 1 if the state deciding whether to fulfill the alliance commitment scores a five or higher on the Polity III democracy scale.49 I select a relatively low threshold of 5 because during the time period under consideration, 1816-1944, democratic characteristics were relatively rare institutional features, and the general levels of democracy in the international system were much lower than in recent years. Maoz argues that one should recognize a moving threshold for democracy over time.50 Even with a threshold of 5, only 19 percent of decision- making states included in this study are democratic.51 I evaluate H2 by including a dummy variable representing whether the decision-making state was a major power according to data provided by the Correlates of War (COW) project.52

Changes Since Alliance Formation

I have argued above that changes experienced by the decision-making state between the date that the alliance is formed and the date that the war begins may make past alliance commitments vulnerable to violation.53 I examine two types of

49. Jaggers and Gurr 1996. I also conducted the analysis using the full twenty-one point scale created by subtracting the polity autocracy score from the democracy score and with varying threshold levels for democracy. These results are reported below. While I obtained yearly democracy and autocracy scores from Polity III, I adjusted some scores if a change in institutional structure occurred during the year. I used Polity 3d to match regime scores to the date of alliance formation and the beginning of war. See McLaughlin et al. 1998.

50. Maoz 1996. 51. Frequencies of this independent variable and all others are listed in the appendix. 52. Small and Singer 1982. I test not only the major power dummy variable, but also continuous

measures of power. Results for both are reported below. 53. If an alliance is formed after a war begins, I code the start date of the alliance-war performance

opportunity to be the date on which the alliance is formed.


changes-changes in domestic institutional structure and changes in power. Be- cause changes in domestic policymaking processes and changes in power are likely to affect the calculations of state leaders in deciding whether to participate in a war, these factors would seem to be particularly likely to call previously secure alliance commitments into question. Changes in regime type and power affect the relationships among the alliance members, the relationships with potential adversaries, and the domestic incentives to pursue varying policies internationally. Ben- nett, Siverson and Starr, and Morrow have demonstrated that these variables influence the duration and termination of alliance commitments.54 This test will examine whether they influence the reliability of alliances that continue to exist as well.

When a previously autocratic state democratizes, or a previously democratic state experiences an autocratic takeover, one can expect changes in foreign policy.55 When an entirely new system of governance emerges, leaders may not feel bound by the commitments of their predecessors. In 1917, for instance, Soviet leaders declared all previous Russian international commitments null and void, immediately abrogating all existing alliance treaties.56 Other times, however, the new leadership does not officially abrogate past treaties and may even declare allegiance to all present international commitments; this may be an important act in achieving international legitimacy for domestic rule. When it comes time to fulfill a particular international commitment, however, new leadership may have a different decision calculus than a predecessor government operating in a different institutional structure. Wars in which an autocratic leader might have been willing to participate may be unpalatable to a democratic leader who is more accountable to the public and more constrained from unilateral action.5' Auto- cratic leaders may be unwilling to assist a democratic coalition in ousting an autocratic leader. The reputational costs that are incurred for breaking agreements internationally and domestically also may be muted when the agreement is associated with the ancien regime. Thus, when a major change in domestic political structure occurs (whether toward democracy or toward autocracy), the reliability of past commitments may come into question, even if the leadership does not officially abrogate the treaties.58

54. See Bennett 1997; Siverson and Starr 1994; and Morrow 1991. 55. Siverson and Starr 1994. 56. Taylor 1954, 566. 57. See, for example, Morgan and Campbell 1991; Russett 1993; Bueno de Mesquita et al. 1999. 58. It is possible that any change in state leadership, even within the same institutional rules (for

instance, the election of a new party to power), might affect foreign policy decision making. In this study, I do not attribute systematic change in foreign policy to changes in leadership within an unchanged domestic institutional structure; any changes in war participation decisions caused by leader personality or platform are accounted for in the error term. My argument instead is based on the claim that different institutional structures encourage and discourage different foreign policy behaviors on the part of all leaders operating within their constraints (for example, Bueno de Mesquita et al. 1999). See Gartzke and Gleditsch 2002 for an alternative argument.


Changes in the relative power of a state may also cause changes in its willingness to fulfill commitments. When states become weaker relative to allies and adversaries, these states may become less willing to join conflicts because their probability of winning or of affecting the outcome of the conflict declines.59 Their allies may be less willing to support them for the same reason. When states become stronger, on the other hand, they may be in less need of an ally's support and come to value the alliance less. When a state no longer needs the cooperation of an ally, protecting that ally is of less importance. Thus, when states experience major changes in their power, either because they have become much stronger or much weaker, they may be less willing to fulfill the alliance commitments they made under different circumstances. Alliances that were valuable at the time of formation may lose value as the initial conditions that promoted cooperation change.

Because I argue that most alliances have a high probability of being fulfilled when they are formed, changes in factors affecting the war decision that have occurred since the alliance was formed are likely to be particularly strong predictors of alliance violation. Changes in two factors should be particularly important- domestic policymaking processes and international power.

H3: Significant changes in the power of a state between the time an alliance is signed and the beginning of a war will be associated with a higher probability of alliance violation.

H4: Changes in the domestic political structure of a state between the time an alliance is signed and the beginning of a war will be associated with a higher probability of alliance violation.

Both of these concepts are captured with dummy variables. If a state is more than 10 percent stronger or 10 percent weaker according to the COW capabilities index at the time of the war than it was when it formed the alliance, I code a change in the power of the state.60 If the state's democracy or autocracy score

59. See Smith 1995 and 1998a; Morrow 1994. 60. For two reasons I employ a dummy variable operationalization for all cases over this threshold

rather than using the absolute value of the percentage change in power. First, I want to ensure that a few outliers with very large changes in power do not have undue influence on the results. I performed the same analysis using the natural log of the absolute value of the percentage change in power. This resulted in a positive and statistically significant coefficient, but the large number of cases with no change in power made this coefficient difficult to interpret (because the natural log of zero is un- defined). Second, it seems reasonable to believe that there is some level of change at which a state will come to reevaluate earlier decisions. Of course, the choice of this threshold is arbitrary. As a result, I ran the analysis choosing thresholds of 5 percent, 10 percent, 20 percent, and 30 percent changes in power. The results are similar in all cases, although the statistical significance declines at 30 percent, probably because of the small number of cases that experience such a large change in power. I report only the results using a threshold of 10 percent here. The COW capabilities index measures the power of a state in relation to the other states in the system; because it is a relative rather than an absolute measure it is not constantly increasing with time.


changes two or more points on the Polity III scale between the time the alliance is formed and the time the war begins, I code a change in domestic political institutions.

Role in War

As noted above, Smith argues that challengers are particularly likely to target states with unreliable allies.61 In this analysis, therefore, I consider whether the allies of the original target in a war are more likely to violate their commitments than are allies of initiators or states that join an ongoing war. If states are more likely to violate their alliance commitments to original targets than to joiners or initiators, the data may suggest support for Smith's argument that challengers identify targets who are less likely to receive allied assistance.62

Yet, Smith's argument is most persuasive if one can understand how challengers identify alliance commitments that are unlikely to be fulfilled. A fully specified model of the probability of alliance violation should include the factors that challengers are likely to look to in evaluating the credibility of alliance commitments. If challengers are able to target states with unreliable allies consistently, it may be because of their ability to observe changes in states that call past commitments into question and characteristics of states associated with violation. When one includes these primary factors that influence the probability of violation in the model, target selection should have a decreased role in explaining the probability of violation. This does not suggest that targets whose allies are unreliable are not more likely to find themselves at war; such a claim must be investigated in a model of war initiation. Rather, I suggest that the targeting variable captures what challengers know about reliability that is not included in the model. As one identifies the factors that influence challenger estimates of reliability, targeting should show up as a less important factor in explaining violation.

H5: All else equal, alliance violation is more likely when a member of the alliance is the original target in a war. In a fully specified model explaining the decision to violate an alliance, however, other factors will better explain alliance violation.

61. See Smith 1995, 1996, and 1998a. 62. Ideally, one would be able to place the entire process of alliance formation, the emergence of

conflict, and alliance reliability in one statistical model that accounts for these selection effects directly. In order for a case to appear in the sample analyzed in this study, states must have chosen to form an alliance, a state must have initiated a dispute, and that dispute must have escalated to war. Smith argues that the sample of allied dyads that become involved in disputes is not a random sample of allied dyads because alliance reliability influences whether disputes are initiated. Yet, because alliance formation also influences dispute initiation and escalation, the sample of allied dyads that become involved in disputes is not a random sample of all dyads either. See Leeds 2003. Thus, to model the selection effects directly, one would need to account for alliance formation, for dispute initiation, and for dispute escalation before one could model alliance reliability.


Using data provided by the COW project on international wars and on militarized interstate disputes, I code any state that is listed as an original participant in a war on the side opposite the initiator of the war as an original target.63

Empirical Results

The results of the analysis are presented in Table 1. The data are supportive of all five hypotheses.64 Both CHANGES IN POWER and CHANGES IN DOMESTIC INSTI-

TUTIONS increase the probability of alliance commitment violation. Some state characteristics are also statistically significant predictors of alliance violation. DEM-

OCRATIC STATES are less likely to violate commitments, while MAJOR POWERS are more likely to fail their allies. While bivariate analysis suggests that alliance part-

TABLE 1. Logit analysis of alliance commitment violation in war, 1816-1944

Estimated coefficient Change in with associated predicted probability

Variables standard error of violation

DEMOCRATIC STATE -2.799** -0.165 (1.143)

MAJOR POWER 1.029* 0.113 (0.640)

CHANGE IN POWER OF STATE SINCE ALLIANCE 2.463*** 0.353 FORMATION (0.551)

CHANGE IN DOMESTIC INSTITUTIONS OF STATE 1.554** 0.235 SINCE ALLIANCE FORMATION (0.572)

ALLY IS ORIGINAL TARGET IN WAR 1.157* 0.154 (0.605)

Constant -3.133 N 143 Chi2 30.90 Percent correctly predicted 86%

Notes: Standard errors are calculated assuming potential nonindependence among cases associated with the same alliance. Change in predicted probability of violation is the absolute change in probability of violation associated with a change from 0 to I in this independent variable when all other variables are held constant at their mean values. ***p < 0.001. **p < 0.01. *p < 0.1.

63. See Singer and Small 1994; and Jones, Bremer, and Singer 1996. 64. Because I am working with a small number of cases and highly skewed dependent and indepen-

dent variables, I was concerned that a few cases might be having undue influence on my results. I measured the change in the coefficient vector that would be caused by deleting particular observations using Pregibon's dbeta. See Pregibon 1981. I reran the analysis deleting the fifteen most influential cases and found virtually no change in the inferences to be drawn from the study.


ners are particularly likely to abandon ORIGINAL TARGETS, the evidence that states are targeted because of unreliable commitments weakens in a model including the factors that allow unreliable alliances to be identified.

I have argued that under most conditions state leaders form alliances that they believe will be reliable. As a result, when one witnesses violated commitments, it may be because one or more of the alliance members has experienced significant changes that affect its decisions regarding participation in war since the alliance was formed. The data are supportive of this argument. The two variables representing changes in the decision-making state between alliance formation and the decision regarding fulfillment are highly significant, both statistically and substan- tively. If a state's power changes 10 percent or more (CHANGES IN POWER), the probability it violates an alliance commitment rises a full 35 percent.65 In other words, the probability that a state does not fulfill its alliance commitment, while a mere 6 percent without any change in power (for the state with average values on all other variables), is a full 41 percent if the state has experienced a change in power of 10 percent or more, nearly a 700 percent increase. Violation is more likely whether the state is becoming weaker or stronger. Variables that separately represent a decrease or increase in power of at least 10 percent are both significant and positively related to alliance commitment violation. Similarly, if the domestic political institutions of a state change (CHANGES IN DOMESTIC INSTITUTIONS), the state's probability of alliance violation rises 24 percent, a 350 percent increase. Again, separate variables representing more democratic and more autocratic governance structures are both statistically significant and positively related to alliance violation.66

In a study by Siverson and King, the age of an alliance was related to violation; older alliances were more likely to be unreliable.67 I tested my model with an additional control variable representing the number of days since the alliance was formed. Notably, variables representing change in power and regime type are more powerful predictors of alliance violation than is a simple variable representing the number of days since an alliance was formed. The correlation between the age of

65. Changes in predicted probabilities are computed holding all other variables constant at their mean values. While no state could actually hold the mean characteristics, this is a better theoretical representation of the "average" state than is a state featuring the modal values on all characteristics. Computing these changes holding all variables constant at their modal values produces substantially similar results with some attenuation, particularly on the influence of democracy. The baseline probability of violation at the modal values, however, is very low (4 percent), indicating that it is not a good representation of an "average" state in the sample.

66. I analyzed whether changes in the domestic institutional structure of the ally that requires support (rather than the ally that must make a decision regarding fulfillment of the terms of the alliance) influence the likelihood of violation and found no statistically significant relationship. In addition, I evaluated whether changes in the capability ratio between the ally requesting support and the ally deciding whether to fulfill the alliance were related to alliance violation, and found no statistically significant relationship. Including these variables does not change the magnitude or statistical significance of the variables reflecting changes in the decision-making state's domestic institutions or power.

67. Siverson and King 1980.


an alliance in days and changes in power and regime are 59 percent and 70 percent respectively. Age is positively associated with violation of alliance commitments, when the variables representing changes in power and regime are not included in the model. When included as a control variable with these change variables, the age of the alliance is statistically insignificant. When age is added as a control variable, the coefficients associated with change in power and change in regime are virtually unchanged. Their associated standard errors do increase (as is predictable with high levels of collinearity), but the coefficients retain statistical significance. Thus, time alone does not explain a propensity to violate commitments. Changes in relevant factors between the time a commitment is made and when it must be fulfilled, however, do put the commitment in jeopardy.

One can also identify particular state characteristics that are associated with alliance reliability. Several scholars have argued that democracies are less likely to break their promises.68 The sample of democratic states in this analysis is small, and I employ a generous threshold value in labeling democracies. However, this preliminary evidence suggests that even in the sample of alliances that states have chosen to form, democratic states are particularly reliable partners. This finding may suggest support for the claim that autocratic states are more willing to form agreements that they may not fulfill; autocratic states may be more likely to bluff.69 The probability of a democratic state breaking a commitment is 16.5 percent lower than the probability of a nondemocratic state doing the same.70

In this sample, major powers are more likely than minor powers to break their alliance commitments." Major powers have an 11 percent greater probability of violation, all else equal, than minor powers. The statistical significance of this finding, however, is weaker than that for the other variables. What suggests further support for the theory advanced in this article, however, is that the difference

68. See Fearon 1994; Gaubatz 1996; Leeds 1999; McGillivray and Smith 2000; and Martin 2000. 69. See Fearon 1994; and Leeds 1999. 70. The interpretation of the results does not change when the full twenty-one point POLITY scale

(created by subtracting the autocracy score from the democracy score) is substituted for the dummy variable. I also performed sensitivity analysis to see whether the results were affected by setting the threshold for democracy at higher levels. Whether the threshold is set at 5, 6, or 7, the signs and significance of the independent variables remain unchanged, with the exception of the major power variable, which loses statistical significance as the democracy threshold is set at higher levels. Only two democratic states violate alliances in my sample-Yugoslavia violates its alliance to Greece in 1940, and Greece violates its alliance to Serbia in 1914. Greece scored a 10 on the POLITY democracy scale in 1914, and Yugoslavia scored a 5 on the POLITY democracy scale in 1940. The correlation between the democracy variable and the major power variable is 0.26. No major power democracies violated alliances in this sample.

71. I performed the same analysis substituting the continuous COW capabilities variable for the dichotomous major power variable. The coefficient for the continuous capability measure is positive, but it does not achieve standard levels of statistical significance. Interpretations of the other variables are unaffected. While this study is instructive for helping one to evaluate the varying arguments linking power and status to the propensity to violate commitments, it is worth noting that the major power result is the least robust to changes in model specification in this study. More research is certainly warranted.


is particularly evident when commitments exist between major powers and minor powers. Major powers are particularly likely to break their commitments to minor powers, whereas minor powers are particularly likely to uphold their commitments to major powers. Promises among major states and among minor states are neither significantly more nor less likely to be violated than the norm.72

The evidence I present would seem to suggest that in asymmetric commitments, the costs of reneging are not equal for major and minor powers. Major powers are more willing to abandon past commitments to minor powers than mi- nor powers are to major powers. Because there is no systematic difference between major and minor powers in symmetric alliances, this finding may be capturing the reluctance of minor powers to violate commitments when they fear retribution from stronger allies. Minor powers find it very costly to abrogate alliances to major powers, whereas major powers find it comparatively easy to abandon their commitments to minor powers than to other major powers.

In the full model, the coefficient for the variable representing whether a state's ally was an original target in the war (ALLY IS ORIGINAL TARGET) is positive and statistically significant with a 90 percent confidence interval. The data seem to suggest that there is some evidence that initiators of conflicts are likely to choose to start wars if the allies of their target are unreliable. Importantly, however, when the variables representing change in institutions and power and the variables representing democracy and major power status are removed from the model, original targets appear to be much more frequent victims of abandonment; the variable representing alliance to an original target is positive and significant at the .01 level. Perhaps this indicates that this analysis has tapped some indicators that challengers use to identify targets that are unlikely to receive allied support. Allies of original targets are more likely to abandon their partners, but this is because other factors (particularly changes since the alliance was formed) have placed their commitments in jeopardy. Those states that initiate wars recognize these signs that alliance commitments may be fragile. The results of this analysis suggest the prof- itability of further investigation in a more fully specified model of war initiation.

The model as a whole successfully predicts 86 percent of the cases: 96 percent of the honored commitments and 46 percent of the violated commitments (see Table 2). Because the sample is highly skewed in favor of honored commitments, with 80.4 percent honored, improving on a null model is difficult. Yet, this model does improve the percentage correctly predicted, and more importantly, it allows one to pick out individual cases that will be violated with some success.73

72. I analyzed separate dummy variables representing decisions by major powers to fulfill or violate commitments to other major powers, decisions by major powers to fulfill or violate commitments to minor powers, decisions by minor powers to fulfill or violate commitments to major powers, and decisions by minor powers to fulfill or violate commitments to other minor powers. The coefficients for the minor-minor and major-major pairs were statistically insignificant. The coefficient for the major- minor pairs was positive and statistically significant at the .05 level. The coefficient for the minor- major pairs was negative and statistically significant at the .05 level.

73. I reviewed the cases that were incorrectly predicted and could not discern any pattern.


TABLE 2. Actual versus predicted values

Model predicts Model predicts commitment honored commitment violated Total

Alliance commitment honored 110 5 115 (95.7%)

Alliance commitment violated 15 13 28 (46.4%)

Total 125 18 143

This empirical evidence, therefore, is commensurate with the argument made in this article. The strongest predictors of a violated alliance are changes in conditions from the time of formation to the time of fulfillment. It also seems to be the case that specific characteristics, particularly democracy, are associated with honoring alliance commitments.

Conclusions and Implications for Future Research

The research presented in this article supports two broad positions on international relations that have often been posed in opposition to one another. Some scholars stress the promise of international cooperation in overcoming anarchy. These scholars claim that institutions and contracting create the ability of state leaders to make credible commitments and avoid the security dilemma inherent in a self-help world.74 On the other hand, other scholars insist that treaties and institutions are not constraining, that they do not hold independent force, and that leaders will be willing to sacrifice treaties when their interests change.75 This research suggests that both may be true. Contracts and institutions are very often fulfilled; treaties are taken quite seriously by their signatories, and state leaders are reluctant to violate commitments. At the same time, when interests change, treaties become more vulnerable to violation. State leaders do not uphold treaties under all circumstances.76

It also appears, however, that the intuition of scholars who doubt the prevalence of bluffing gains some empirical support.77 Bluffing seems to be a fairly rare phe- nomenon in alliance politics. Not only do 80 percent of allied states who face a decision to honor or violate their alliance commitments in war fulfill their com-

74. For example, Keohane and Martin 1995. 75. For example, Mearsheimer 1995. 76. While the results of this test suggest that when interests change alliances are in jeopardy, this

test is silent on whether forming alliances changes behavior. Examining that question would require comparing behavior at the initial conditions with and without an alliance.

77. For example, Fearon 1997.


mitments, but many of the remaining violations can be accounted for by changed circumstances between alliance formation and invocation. Because an alternative explanation accounts well for so many violations, one can draw the conclusion that only a portion of the 20 percent of decisions to violate commitments were bluffs that were called. It seems increasingly unlikely that states frequently form alliances that they are unwilling to fulfill.

Rather, the evidence is supportive of theories of alliance formation that anticipate that alliances will be reliable. Contemporary theories that find the motivation for alliance formation in the desire to signal future intentions through costly actions and those that find the motivation in the gains produced from institutionalized cooperation agree that most states that form alliances are likely to fulfill them. This study provides further support for these research programs.

Future research should pursue several lines of inquiry. First, the fact that most alliance treaties are reliable and that state leaders uphold the promises that they make under most circumstances should encourage the investigation of the conditions under which leaders are willing to form agreements and the means by which they design credible agreements. There is efficacy in international cooperation; designing self-enforcing agreements is possible and worthwhile. Scholars should design research that explains how leaders can overcome the risks of opportunism and design agreements that they and their partners will have incentives to fulfill.

At the same time, state leaders should be vigilant regarding crucial changes in the incentives facing themselves and their partners during the terms of ongoing agreements. While agreements may exert some independent force on behavior, as conditions change, violation becomes more likely. Reassessing policy as incentives change remains important.

Thus, this study suggests that recent attempts to move beyond the simple question "do institutions matter?" that inspired considerable realist-institutionalist de- bate78 is worthwhile. Research that focuses more specifically on the conditions under which institutions are effective and the design of effective institutions will move the field forward.79 Because institutions are neither always epiphenomenal nor always constraining, knowing more about the conditions under which leaders will and will not comply with institutional obligations will help scholars and prac- titioners to focus their efforts and to bring about and anticipate policy outcomes.

This study also provides information regarding the escalation and diffusion of conflict. Leaders should assume that under most conditions, allies will fulfill their promises. This means that engaging a state in war when allies have promised to intervene is a proposition that entails a significant risk of war expansion. It also means that the deterrent and compellent properties of alliances should be taken quite seriously.

78. For example, Mearsheimer 1995; and Keohane and Martin 1995. 79. See, for example, Koremenos, Lipson, and Snidal 2001.


While this study raises a number of questions that remain to be answered in more fully specified studies of alliance formation, war initiation, and war expansion, it also provides significant leverage over questions regarding the reliability of international agreements and the conditions under which state leaders are most likely to violate past commitments. The cooperative agreements that state leaders are willing to form tend to be fulfilled; most promises are upheld, even under anarchy. At the same time, some types of states may be more willing to violate commitments than others, and changes in relevant conditions can cause leaders to reevaluate their policies and abrogate their treaties.

Appendix: Frequencies of Independent Variables

Variable 1 0 Total

DEMOCRATIC STATE 27 116 143 18.9%

MAJOR POWER 57 86 143 39.9%

CHANGE IN POWER OF STATE SINCE ALLIANCE FORMATION 45 98 143 31.5%

CHANGE IN DOMESTIC INSTITUTIONS OF STATE SINCE ALLIANCE FORMATION 19 124 143 13.3%

ALLY IS ORIGINAL TARGET IN WAR 26 117 143

18.2%

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Documents

International Organization Foundation - … International Organization The Formation and Fulfillment of Alliance Agreements History is full of examples of cases in which state leaders