What determines the volumes of international weapon transfers? And why do countries establish such arms trading relationships in the first place? We propose an innovative statistical strategy that builds on the gravity approach and combines a Heckman model with a network analysis. This allows us, for the first time, to analyze the impact of network structures on both the extensive and the intensive margins of the international arms trade simultaneously. We argue that the structure of the arms transfer network conveys important information for exporting and importing countries. Therefore, past topological properties of the trade network play a central role in its future evolution. Using data on the trade of major conventional weapons between 1955 and 2018, our estimation results and out-of-sample predictions show that network structures have considerable explanatory power with respect to the creation of trade links. They are far less relevant for the explanation of trade volumes, which are mainly determined by demand factors.

什么决定了国际武器转让的数量？为什么各国首先要建立这种武器贸易关系？我们提出了一种创新的统计策略，该策略建立在重力方法的基础上，并将 Heckman 模型与网络分析相结合。这使我们第一次能够同时分析网络结构对国际武器贸易的粗放边际和集约边际的影响。我们认为，武器转让网络的结构为出口国和进口国传达了重要信息。因此，贸易网络过去的拓扑特性在其未来的演变中起着核心作用。使用 1955 年至 2018 年间主要常规武器贸易的数据，我们的估计结果和样本外预测表明，网络结构对贸易联系的建立具有相当大的解释力。它们与解释贸易量的相关性要小得多，贸易量主要由需求因素决定。