Alliance Reliability and Dispute Escalation

• Author: Jesse C Johnson,Scott Wolford
• DOI: http://doi.org/10.1177/00220027221121140
• Published date: 01 April 2023
• Date: 01 April 2023
• Subject Matter: Articles

Article

Journal of Conf‌lict Resolution

2023, Vol. 67(4) 617–641

© The Author(s) 2022

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DOI: 10.1177/00220027221121140

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Alliance Reliability and

Dispute Escalation

Jesse C Johnson

1

and Scott Wolford

2



Abstract

States form defensive alliances hoping to deter adversaries and avoid war. However,

scholars and policy analysts often worry that if an alliance fails to deter the promise of

military support will encourage escalation, pushing disputants closer to war. We show

that in many cases this concern is unwarranted. We use a game-theoretic model of

alliance reliability and crisis bargaining to show that the same factors that indicate

unreliability and provoke disputes also encourage alliance members to make con-

cessions rather than risk war. We test this hypothesis using a sample of militarized

disputes initiated against members of defensive alliances, where recent shifts in military

capabilities represent changes in challengers’estimates of alliance reliability. Less-

reliable alliances are less likely than reliable allies to deter disputes, but they also

decrease the probability of escalation relative to reliable alliances. Unreliable alliances

need not encourage war; rather, they can discourage it.

Keywords

alliance, war, deterrence, game theory

Signing defensive alliances entails an apparent tradeoff. By providing members with

promises of military support in the event of war, an alliance can bolster general de-

terrence, discouraging opponents from trying to change the status quo with force

(Johnson and Leeds 2011;Leeds 2003;Wright and Rider 2014). When alliances fail to

1

Department of Political Science, University of Kentucky, Lexington, KY, USA

2

Department of Government, University of Texas, Austin, TX, USA

Corresponding Author:

Scott Wolford, Department of Government, University of Texas, 158 West 21st St, A1800 Austin, TX

78712, USA.

Email: swolford@austin.utexas.edu

deter, however, promises of military support may embolden allies and encourage them

to escalate the dispute, pushing disputants closer to war (Senese and Vasquez 2004,

2008;Smith 1995). It seems that defensive alliances might help states avoid some

disputes, but the ones that emerge may be particularly severe.

1

This deterrence-escalation tradeoff may seem intuitive, but the argument rests on

an assumption that only challengers—not their targets—condition their behavior on

an ally’s expected reliability. One of the main reasons an alliance can fail to deter is if

an ally is perceived to be unreliable (Clare 2013;Johnson, Leeds, and Wu 2015;

Johnson and Joiner 2019;Quackenbush 2006). If an opponent doubts the reliability of

an alliance, it will be more conf‌ident in its chances of military victory against its target

and, thus, more willing to rely on military power to challenge the status quo. But

beliefs about alliance reliability should also affect allies’decisions to escalate dis-

putes (see Smith 1996,1998), discouraging states with unreliable allies from es-

calation precisely because they believe those allies might abandon them and

alleviating the tradeoff.

We explore this possibility in a game-theoretic model that isolates the effect of

beliefs about alliance reliability on dispute onset and escalation (cf. Kenwick and

Vasquez 2017). We show that, if (a) challengers initiate disputes against targets with

allies believed to be unreliable and (b) targets know at least as much as challengers

about their own allies’reliability, then (c) the same factor that encourages the ini-

tiation of disputes also discourages their escalation. Challengers are more likely to

initiate disputes against targets with unreliable allies than reliable ones, yet targets

with unreliable allies are also driven to moderate their bargaining postures, reducing

the chances of a war in which allies abandon them. In other words, any factor that

causes both challenger and target to doubt an ally’s reliability should correlate

positively with dispute initiation—that is, deterrence failure—and negatively with

dispute escalation.

We test our hypotheses with a unif‌ied empirical model of dispute initiation and

escalation among directed dyad-years involving state members of the international

system from 1816-2000 (COW 2017). Our key theoretical variable measures changes

in ally military capabilities, an observable, commonly known shock to the strategic

environment that reduces observers’estimates of an alliance’s reliability. States that

grow substantially stronger or weaker may revise downward their valuation of a given

commitment, rendering their allies’enemies optimistic that the alliance is no longer

credible. Indeed, changes in military capabilities, positive and negative, are one of the

strongest predictors of alliance violations in time of war (Leeds 2003). We uncover

patterns in the data consistent with our hypotheses. First, unreliable alliances are

uniquely likely to be targeted in disputes (Johnson, Leeds, and Wu 2015;Johnson and

Joiner 2019). Second, unreliable alliances are also the least likely to see their disputes

escalate. We provide evidence that arguments linking alliances to a deterrence-

escalation tradeoff (e.g. Vasquez 1993,2009) omit a key variable—an alliance’s

expected reliability—that explains why the alliances least likely to deter are also those

whose disputes are least likely to escalate.

618 Journal of Conf‌lict Resolution 67(4)