State support to non-state armed groups outside the state’s own territory is commonly seen as a direct relationship between a state sponsor and a rebel group. But powerful states can use a third state—a dealer or broker—as a conduit for military and other rebel support. Powerful states face a double principal-agent problem when providing material support to rebels if the intermediary has its own agenda. States that fail to identify an alignment of interests with the intermediary dealers and brokers face strategic failure.
Niklas Karlén and Vladimir Rauta, "Dealers and Brokers in Civil Wars: Why States Delegate Rebel Support to Conduit Countries," International Security 47, no. 4 (Spring 2023): 107–146, https://doi.org/10.1162/isec_a_00461.