Bilateral defense cooperation agreements, or DCAs, are now the most common form of institutionalized defense cooperation. These formal agreements establish broad defense-oriented legal frameworks between signatories, facilitating cooperation in such fundamental areas as defense policy coordination, research and development, joint military exercises, education and training, arms procurement, and exchange of classified information. Although nearly a thousand DCAs are currently in force, with potentially wide-ranging impacts on national and international security outcomes, DCAs have been largely ignored by scholars. Why have DCAs proliferated? I develop a theory that integrates cooperation theory with insights from social network analysis. Shifts in the global security environment since the 1980s have fueled demand for DCAs. States use DCAs to modernize their militaries, respond to shared security threats, and establish security umbrellas with like-minded states. Yet, demand alone cannot explain DCA proliferation; to cooperate, governments must also overcome dilemmas of mistrust and distributional conflicts. I show that network influences increase the supply of DCAs by providing governments with information about the trustworthiness of partners and the risk of asymmetric distributions of gains. DCAs become easier to sign as more states sign them. I identify two specific network influences - preferential attachment and triadic closure - and show that these influences are largely responsible for the post-Cold War diffusion of DCAs. Novel empirical strategies further indicate that these influences derive from the proposed informational mechanism. States use the DCA ties of others to glean information about prospective defense partners, thus endogenously fueling further growth of the global DCA network.

The study of trade and conflict has largely focused on dyadic interdependence, or trade within discrete pairs of states. Yet, states may also be indirectly interdependent, by way of trade to third parties. This paper examines the influence of third-party trade on dyadic conflict initiation. I argue that certain structures of trade provide economically invested third parties with (1) an incentive to discourage dyadic conflict between a potential initiator and a potential target, and (2) the means to show disapproval of conflict by sending trade-based signals of resolve. The argument thus emphasizes the ability of third parties to introduce novel ex post information into bargaining dynamics, causing potential aggressors to reconsider their conflict strategies. Empirical analysis shows that, in fact, when a given dyad shares the sort of trade structures that enable costly signaling by third parties, the probability of conflict initiation declines substantially. In contrast, when third-party trade merely increases a potential initiator's opportunity costs for conflict, conflict behavior remains unchanged. © The Author(s) 2013.

Existing studies of intergovernmental organizations (IGOs) and militarized conflict focus on dyadic counts of shared IGO membership. However, dyadic approaches are inconsistent with the basic properties of IGOs. Because IGOs are multilateral organizations, shared membership necessarily involves ties to third parties. This article employs network analytics to develop a novel explanation of how third-party IGO ties reduce militarized conflict. The analysis first examines the 'structural similarity' of states, defined by the extent to which states share similar patterns of IGO membership with relevant third parties. High levels of structural similarity indicate that states interact with a common set of IGO collaborators. The analysis then shows that micro-level changes in IGO membership effect changes in structural similarity, leading to the macro-level phenomenon of 'network convergence,' wherein states increasingly collaborate with the same third parties over time. Substantively, convergence results in increased overlap and integration between states' respective local networks of IGO partners. Because network convergence is costly, involving a combination of IGO-based accession, sovereignty, and alignment costs, it is unlikely to be pursued by purely exploitative state types. Consequently, convergence provides cooperative types with a mechanism for signaling a preference for cooperation over conflict. These credible signals in turn establish mutual trust among cooperators and effectively reduce the risk of militarized conflict. Extensive empirical analysis shows that, in fact, network convergence strongly correlates with a decline in militarized dispute initiations. The more that states collaborate with one another's IGO partners, the less likely they are to fight. © The Author(s) 2013.

The academic study of defense cooperation focuses heavily on formal military alliances. Yet, governments rarely sign new alliances, and the global alliance structure has remained relatively static for decades. By contrast, governments are increasingly active in defense cooperation agreements (DCAs). These bilateral framework treaties institutionalize their signatories’ day-to-day defense relations, facilitating such wide-ranging activities as defense policy coordination, joint research and development, weapons production and arms trade, joint military exercises, training and exchange programs, peacekeeping, and information exchange. Nearly 2,000 DCAs have been signed since 1980. Preliminary evidence suggests that DCAs impact numerous security, military, and defense outcomes and that governments increasingly incorporate DCAs as core elements of their security strategies. This article introduces the new DCA Dataset (DCAD). I provide a brief historical background on DCAs and compare them to other commonly studied forms of defense cooperation. I then explain coding standards and describe the data set in detail. Finally, I illustrate applications of DCAD to militarized interstate disputes and arms trade.

Cooperation helps states realize mutual gains, but mistrust and disagreements over institutional design inhibit cooperation. This article develops a network explanation for how states achieve cooperation in the face of persistent coordination and collaboration problems. The analysis focuses on bilateral cooperation agreements, a vast body of treaties spanning multiple issue areas. Bilateral agreements constitute an evolving network of cooperative ties. This network defines the strategic environment in which states bargain over new agreements, endogenously influencing subsequent bilateral endeavors by revealing strategically valuable information about states' trustworthiness and preferences over institutional design, while also generating externalities that incentivize bilateral partnerships. Inferential network analysis shows that states are more likely to create bilateral agreements if they (1) share agreements with common third parties, (2) accede to more agreements in general, and/or (3) share important exogenous characteristics with current bilateral partners. These network dynamics drive bilateral cooperation in everything from commodities to cultural exchange to fisheries. © 2013 American Political Science Association.

This article assesses the impact of a new form of defense cooperation – formal weapons cooperation agreements, or WCAs – on the global arms trade. WCAs are bilateral framework agreements that establish comprehensive guidelines on the development, production, and exchange of conventional arms. Substantively, WCAs regulate such core areas as procurement and contracting, defense-based research and development, and defense industrial cooperation. These agreements have proliferated dramatically since the mid-1990s. They now number nearly 700, with 30–40 new WCAs signed each year. Newly collected data are used to analyze the effect of WCAs on import and export of conventional weapons. To control for interdependencies in the formation of WCAs, and to account for the mutually endogenous relationship between WCAs and weapons flows, WCAs are modeled as an interdependent network that coevolves with the individual-level arms trade activity of states. The analysis shows that, over the 1995–2010 period, WCAs have significantly increased weapons flows.

This article assesses the impact of a new form of defense cooperation – formal weapons cooperation agreements, or WCAs – on the global arms trade. WCAs are bilateral framework agreements that establish comprehensive guidelines on the development, production, and exchange of conventional arms. Substantively, WCAs regulate such core areas as procurement and contracting, defense-based research and development, and defense industrial cooperation. These agreements have proliferated dramatically since the mid-1990s. They now number nearly 700, with 30–40 new WCAs signed each year. Newly collected data are used to analyze the effect of WCAs on import and export of conventional weapons. To control for interdependencies in the formation of WCAs, and to account for the mutually endogenous relationship between WCAs and weapons flows, WCAs are modeled as an interdependent network that coevolves with the individual-level arms trade activity of states. The analysis shows that, over the 1995–2010 period, WCAs have significantly increased weapons flows.

Abstract: Why do some international agreements yield more cooperation than others? I argue that the network context of agreements conditions their effectiveness. I focus on bilateral defense cooperation agreements (DCAs), which promote defense activities like joint military exercises, peacekeeping, arms trade, and the sharing of classified information. Because DCAs emphasize ongoing cooperative actions, they offer an ideal setting to assess treaty effectiveness. The analysis shows that when agreements are embedded in transitive “friend of friend” relations, characterized by extensive ties to common third parties, they generate higher levels of cooperation. I argue that this network effect is the result of policy convergence. When states share ties with common third parties, their own policies become more closely aligned, and this alignment in turn reduces the costs and increases the benefits of cooperative actions. The theory and findings developed here apply to a wide array of cooperative interactions across multiple issue areas. The effectiveness of international agreements depends on network context.

The potential for mutual influence or “spillover” between economic and security cooperation is a longstanding area of interest for policymakers and scholars alike. This paper examines how network dynamics affect spillover. We focus on two prominent types of formal bilateral cooperation—defense cooperation agreements (DCAs) and bilateral investment treaties (BITs)—both of which have proliferated dramatically in the post-Cold War international system. We argue that existing theoretical and empirical approaches to economic-security spillover focus too strictly on influences at the bilateral level. As with other forms of international cooperation, BITs and DCAs comprise larger international networks. Governments develop portfolios of BITs or DCAs with distinct structural goals in mind, and they implement specific strategies in pursuing those goals. With BITs, governments follow a network-hierarchy strategy that allows them to influence treaty design and protect their firms. In DCAs, governments instead favor a network-community strategy focused on pooling collective security goods among groups of like-minded collaborators. When these network strategies complement one another, they promote cooperative economic-security spillover. When they conflict, however, they inhibit spillover, such that cooperation in economic or security issues discourages cooperation in the opposing issue area.

When do domestic events affect international relations? Our answer to this puzzle emphasizes patterns of interaction in domestic networks. Leaders depend on coalitions of subnational actors—civilians, parties, militaries, and so on—for political survival. Structural imbalance emerges when the higher-order relations of subnational actors contradict their revealed preferences, such as when actors cooperate with enemies of friends or conflict with friends of friends. Imbalance generates uncertainty about the preferences and future behaviors of subnational actors, which in turn diminishes the government’s confidence in domestic coalitions. Imbalance thus increases the probability that leaders will turn to survival strategies, such as manipulating foreign relations in order to show competence. At the same time, foreign governments respond to imbalance by implementing preventive measures or intervening for strategic gain. We develop and test these arguments from a networks-of-networks approach. We introduce generalizable metrics of structural imbalance and foreign-relations shifts. Extensive empirical analysis shows that the greater the imbalance generated by domestic events, the greater the probability that those events will affect foreign relations.