Understanding reneging: Canada's nuclear sharing commitments to NATO and NORAD during the Cold War

How and why do leaders renege on their alliance commitments, despite institutional incentives to cooperate? According to the research on alliance reliability, three types of costs discourage reneging: material costs, reputational costs, and domestic audience costs. These costs are theorized to be especially high for leaders of democracies, junior alliance members, and members of highly institutionalized alliances. Yet, despite these characteristics, Canada's foreign policy related to its nuclear sharing commitments to NATO and NORAD between 1957 to 1984 was uneven. It included several instances of reneging or attempted reneging. Through an in-depth analysis of archival material related to Canada's nuclear alliance commitments, I propose a new theory of reneging. I show that a leader's decision to renege, choice of bargaining strategy in intra-alliance negotiations, and likelihood of success are related to the type of domestic coalition that supports reneging. Leaders with the support of nationalist domestic coalitions face fewer audience costs for reneging and have more leverage when bargaining with allies than those with the support of single-issue or anti-nuclear coalitions. Nationalist coalitions provide negotiators with three key sources of bargaining power in intra-alliance negotiations: a credible threat of withdrawal, a willingness to act unilaterally, and a low vulnerability to being swayed by foreign allies. On the other hand, single-issue coalitions do not wish to leave the alliance, are more willing to act through alliance consensus, and are more vulnerable to allies' attempts to in uence their stance.