When do NATO members underinvest in collaborative armament procurement? While conventional wisdom suggests that security institutions foster collaboration through interest convergence and standardization, post-Cold War data reveals that former Warsaw Pact members rarely engage in weapons acquisitions collaboration. This article demonstrates that institutional incentives failed to overcome their divergent interests and historical legacies. I argue that armament collaboration is a strategic tool for risk management: states pursue it to secure stable supply chains. In Central and Eastern Europe, such collaboration remains rare due to the availability of independent U.S. security guarantees, the post-1991 erosion of domestic defense industrial bases, and the fact that Western arms exporters largely viewed the region's strategic value as contested before the 2014 Crimean crisis. Using a mixed-methods design, I first utilize a novel dataset of disaggregated defense expenditures to demonstrate this pattern of underinvestment in collaborative weapons acquisitions. I then employ case studies of the Visegrad Group, drawing on elite interviews and primary sources, to show that these states favor bilateral deals to reciprocate extraregional security commitments rather than pursuing collective interoperability. This study advances our understanding of alliance burden-sharing and the political economy of defense acquisitions.

What drives a state’s weapons acquisition strategy? States are often concerned about being cut off from their weapons suppliers when security interests diverge. As a result, they are strongly motivated to produce weapons domestically rather than rely on external sources. However, not all states can resolve this concern through import substitution. This article argues that a state's decision to make or buy weapons depends on both its relationship with major suppliers and its capacity to develop and produce weapons. States facing diverging interests but lacking sufficient defense industrial capabilities often initiate defense industrialization efforts to catch up. At the same time, they tend to maintain relationships with major suppliers to access technological input, to eventually replace those sources. However, when weapons programs become overly ambitious, dependence may persist. This article draws on archival evidence to examine how Japan, South Korea, and Taiwan developed new naval capabilities in the wake of the 1969 Nixon Doctrine. Specifically, it investigates Japan’s P-3C, South Korea’s FFK-1, and Taiwan’s PFG-1 programs. While Japan maintained its dependence on the US, given its strong relationship with the United States, South Korea and Taiwan launched indigenous programs to mitigate fears of abandonment. Taiwan, however, ultimately halted its plan for full domestic production due to doctrinal shifts and fiscal and technological constraints. In contrast, South Korea successfully completed the domestic production program and expanded its defense sectors.

When do states reveal their military capabilities? States often showcase military capabilities for coercive purposes. Yet, doing so risks exposing sensitive advantages and forfeiting the element of surprise. This study introduces a missing dimension in this strategic calculus: experimentation. Militaries have ongoing needs to test doctrines, operational concepts, and weapons systems. Revealing military capabilities during coercive operations can therefore serve as an opportunity to train forces in realistic conditions. Such decisions are most likely when the risk of escalation is low and when exercises can approximate wartime environments. To test these arguments, I leverage an original dataset tracing China’s daily military campaign in the Taiwan Strait from 2020 to 2024. Using a two-stage regression framework, I show that internal operational demands drive China’s decisions to reveal new military capabilities, while foreign challenges primarily shape the scale of its operations. This research advances our understanding of military behavior by distinguishing routinized training and experimentation from strategic coercion, and by linking the foundations of military planning with the logic of deterrence and signaling. 

Why do states form non-binding agreements for long-term interstate cooperation? In this research, we propose a new typology of commitment. We conceptualize soft commitments as those characterized by high publicity and low formality. The flexibility afforded by low formality encourages states to explore cooperative relationships, while high publicity imposes audience costs to disincentivize non-compliance. Accordingly, these agreements are most likely to emerge between states with differing regime types, where information asymmetry is acute and commitment is difficult to evaluate. Furthermore, states use soft commitments to strengthen existing ties while hedging by forming agreements with non-hub states in the network. To evaluate these arguments, we implement temporal exponential random graph models (TERGMs) using an original dataset of over 1,400 global strategic partnership agreements from 1990 to 2024. We find that states are more likely to partner with those possessing differing regime types and greater trade flows. Furthermore, structural terms indicate that strategic partnerships emerge around local hubs. We buttress these empirical results with a case study of the evolution of the Sino-Indian strategic partnership. Our article contributes to the literature on international cooperation by adopting a multi-method approach and broadening our understanding of state behavior in the era of great power competition.

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