The internationalization of intrastate conflict: A network perspective on empirical evidence and theoretical explanations

The internationalization of intrastate conflicts has become a defining trend in 21st-century organized violence, marked by external actors providing militarily relevant support—such as troops, arms, or intelligence—to domestic warring parties. While research examines various dimensions of this phenomenon, systematic analysis of macro-level trends and their drivers remains limited. This article addresses this gap through three contributions. First, it introduces a network-based framework to conceptualize forms of internationalization and identify potential explanations. Second, it demonstrates empirically that intrastate conflicts have indeed become more internationalized across multiple measures. Third, it synthesizes research to identify and evaluate likely drivers of this trend. The study provides the first systematic framework for understanding internationalization as a network phenomenon and establishes a foundation for future research on external involvement in civil wars. By unifying fragmented research through a coherent analytical lens, the article advances both theoretical and empirical understanding of contemporary conflict dynamics.