Jesse C. Johnson

To concede or to resist? The restraining effect of military alliances

Creating institutions that effectively manage interstate conflict is a priority for policy-makers. In this article we demonstrate that military allies are well positioned to influence the crisis-bargaining behavior of both challengers and targets in ways that often lead to peace. Through a three-player game-theoretic model, we demonstrate that a targets alliances not only have an effect on the demand that the challenger makes, but also on the behavior of the target. When a target values an alliance highly, an allys recommendation for settlement can encourage the target to concede to demands without further escalation. Our statistical analysis provides evidence in support of the theoretical finding. Allies can both deter challengers and restrain partners, and as a result, can encourage peaceful behavior not only from adversaries, but from member states as well. Our study thus sheds new light on the role of military alliances as potential conflict management devices.

Capability, Credibility, and Extended General Deterrence

Deterrence theory suggests that extended general deterrent threats are likely to be more effective when a potential challenger views them as capable and credible. When states sign formal defense pacts, they are making explicit extended general deterrent threats. Thus, the population of defense pacts allows us an opportunity to judge the efficacy of extended deterrent threats with different characteristics. We find that defense pacts with more capability and more credibility reduce the probability that a member state will be a target of a militarized dispute. We also find that states can affect the capability and credibility of their extended deterrent threats through alliance design. Members of defense pacts that include higher levels of peacetime military coordination are less likely to be attacked. This analysis provides support for deterrence theory in the context of extended general deterrence. It also provides evidence that should aid policymakers in designing security structures to meet their goals.

Responsibility and the Diversionary Use of Force1

Do state leaders use force abroad to divert supporters’ attention from domestic economic problems? Many studies in international relations attempt to provide an answer to this question but the empirical findings are inconsistent. In this article we argue that it is necessary to consider variations in supporters’ perceptions of leaders’ control of the economy to understand leaders’ incentives to engage in the diversionary use of force. Leaders that are perceived to have high levels of responsibility for the economy will be more likely to use force abroad in the presence of domestic economic problems than leaders that are perceived to have lower levels of responsibility. When leaders are not perceived to have high levels of responsibility they do not have an incentive to use force abroad in the presence of domestic economic problems because the economic problems will not affect the probability that they will retain power. A directed dyad analysis of conflict initiation from 1950 to 1998 supports this hypothesis. This study improves our understanding of patterns of international conflict and, more specifically, the diversionary use of force, by demonstrating the contexts in which diversionary incentives will be strongest.

The cost of security

It is well recognized that military alliances can provide their members with important security benefits. However, less attention has been paid to the policy concessions states must grant others to enter into military alliances. To study this aspect of alliances, I develop a three-actor bargaining model of alliance formation that endogenizes both external threat and policy concessions. Specifically, a target state bargains with a potential defender over the concessions it must make to ally and then responds to a potential challenger. The model suggests that what is important for policy concessions in alliances is not just the power of the threatened state but its power relative to its challenger and how an alliance will change the distribution of power. I test implications of this model using data on promised policy concessions formalized in alliance treaties and find strong support for the hypotheses. More specifically, I find that states are willing to make more concessions in exchange for an alliance when they are unlikely to defeat their challengers alone and when their allies have a large effect on their probability of winning in war. These findings refine existing theories of alliances and offer the first large-N analysis of policy concessions in alliances.

Careful Commitments: Democratic States and Alliance Design

Evidence suggests that leaders of democratic states experience high costs from violating past commitments. We argue that because democratic leaders foresee the costs of violation, they are careful to design agreements they expect to have a high probability of fulfilling. This may cause democratic leaders to prefer flexible or limited commitments. We evaluate our argument by analyzing the design of alliance treaties signed by countries of the world between 1815 and 2003. We find that alliances formed among democratic states are more likely to include obligations for future consultation rather than precommitting leaders to active conflict, and defense pacts formed among democratic states are more likely to specify limits to the conditions under which member states must join their partners in conflict. This research suggests that separating screening effects and constraining effects of international agreements is even more difficult than previously believed. States with the greatest likelihood of being constrained are more carefully screened.

Theory, Data, and Deterrence: A Response to Kenwick, Vasquez, and Powers

Kenwick, Vasquez, and Powers question whether empirical evidence supports the claim that defense pacts deter conflict as our prior research has concluded. We review the theoretical argument for why defense pacts should deter conflict and consider the challenges inherent in evaluating deterrence using observational data. We then consider whether the research design choices of Kenwick et al. improve upon our research design. We demonstrate that claims that defense pacts deter conflict are robust to many of these changes in research design, and we argue that the consequential difference, while perhaps appropriate for testing the Steps-to-War argument, is not appropriate for testing the deterrent effect of defense pacts. We conclude by noting that a deterrence effect of defense pacts is not necessarily incompatible with aspects of the Steps-to-War argument, and we suggest profitable new directions for testing the Steps-to-War approach.

Alliance treaty obligations and war intervention

Theories of alliance formation and war suggest that alliances influence the probability that a potential challenger will initiate a militarized interstate dispute. This is because alliances are expected to influence their members’ likelihood of intervening in a potential war. More specifically, defense pacts are expected to increase the likelihood of members joining the target of a war and offense pacts are expected to increase the likelihood of members joining the initiator of a war. However, there is no empirical evidence that demonstrates that these different alliance treaty obligations have these effects on states’ war intervention decisions. Therefore, in an analysis of all states’ war intervention behavior in 95 wars, I provide the first estimates of these different effects of alliance agreements. After controlling for a number of measured and unmeasured factors, I find that alliances have the hypothesized effects on states’ war intervention decisions. These findings provide a more comprehensive account of the effects of alliances on war intervention and offer additional support for arguments linking alliances to the onset of militarized interstate disputes.