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

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.

A winning proposition? States’ military effectiveness and the reliability of their allies

“…Even in the highly successful case of NATO, French vacillation can be seen as evidence of the importance of post-ratification changes in incentives. Leeds (2003) provides a logical framework that clarifies the connection between the causes of violation established in prior empirical work and the formal arguments made by Morrow, Smith and Fearon. She argues that the fact that alliances are violated in approximately 25 per cent of the instances in which their terms are in effect generally supports the notion that alliances are reliable agreements, but that the remaining violations are still in need of explanation. She argues that violations can be explained by reference to two forces: bluffing and changes after signing.…”

“…This mismatch between formal theoretical expectations and the observed frequency of alliance violation may be owing to sampling, as suggested by Smith (1995, p. 418), or may be because of factors that change over the course of the alliance (Leeds, 2003). It is the latter explanation that is the focus of this article.…”

“…1 While the theoretical framework and empirical findings offered by Leeds (2003) respond to Fearon's speculation, another branch of work has developed with the goal of explaining the violations that we do observe, only partly responding to formal work on the topic.…”

“…The second path has tackled the empirical existence of moderate levels of violation, exploring the impact of a set of explanatory factors like regime change, regime type and changes in the balance of power after signing. Leeds (2003) sets up the mismatch between formal work on alliances and empirical findings on alliance violation. Morrow (1994) describes alliances as costly signals of common interests among allies.…”

“…It is the latter explanation that is the focus of this article. Specifically, I adopt the theoretical framework offered by Leeds (Leeds, 2003), which separates causes of violation into factors that change over the course of the alliance and factors that influence the costs of violation. Extending the costs side of the theoretical argument, I argue that states consider the potential costs of violating or honoring their alliances and that one way in which they calculate those costs is by referring to the record of military effectiveness of the ally in need of assistance.…”