Why do states augment their formal alliance commitments with material arms transfers in some cases but not others? Existing work focuses on the informational value of arms transfers, viewing them as costly signals of an ally's commitment to the protege. In this paper, I provide a distinct, complete-information explanation: arms transfers alter the balance of power and can mitigate power shifts, eliminating commitment problems. To do this, I develop a formal model in which a defender, protege, and challenger interact repeatedly over an infinite horizon. When the future balance of power is certain, the ally never transfers arms. However, when a power shift is expected, arms transfers may occur in equilibrium as they prevent the protege from initiating a preventive war. I then use the theoretical results to shed light on historical patterns of arms transfers between major powers and their proteges.
How does the development of nuclear latency - the ability to build nuclear weapons - affect a state’s ability to secure a place under the U.S. nuclear umbrella? The United States’ has long opposed nuclear proliferation. However, empirically, many U.S. allies have chosen to research and develop nuclear capabilities. Existing theories do not account for the interrelated strategic choices to enter alliances and to pursue nuclear weapons, nor do empirical estimates incorporate this strategic behavior. This paper constructs a strategic probit model based on a new theory in which weaker states strategically manipulate nuclear latency to influence strong states' alliance offers. Strong states select weak states into alliances based on latency to change their nuclear development calculus. The estimates overturn two pieces of conventional wisdom. First, nuclear latency can reverse the traditional fears of abandonment and push past entrapment concerns in uncertain security environments to drive alliance formation. Second, I show that high latency states that are militarily strong can use latency to secure alliance guarantees.
What are the origins of the United States alliance with Australia and New Zealand, and what do they reveal about the trade-offs of bilateral and multilateral alliance designs? International Relations scholarship has almost exclusively focussed on European alliances prior to 1945 and Washington’s alliances with its NATO allies, Japan, South Korea and Taiwan since then. Literature that puzzles at multilateralism in Europe and bilateralism in Asia is either inconclusive or cannot explain why by 1951 Truman ultimately wanted Japan and many of its wartime adversaries in a multilateral alliance. This paper makes two contributions. First, it contributes to debates about threat perception by showing that Australian insecurities in the early Cold War were mostly directed not at Moscow or Beijing but Australia’s then vanquished wartime adversary Japan. Second, it argues that bilateralism may offer greater insurance against entrapment but carries additional assurance costs. Truman could not achieve a multilateral alliance in Asia because Australia and others would not join an alliance with Japan. Their consent to the Japan settlement required additional alliances that raised assurance problems.