External state support to non-state armed groups is commonly seen as a direct relationship between a state sponsor and a rebel group. But powerful states often use third-party states as conduits of military aid. These intermediary states are secondary, subordinate principals that are part of extended chains of “dual delegation.” Because intermediaries are likely to have their own separate agendas, powerful states often face a double principal-agent problem when providing material support to rebel groups. The difficulties and problems associated with controlling the agent are reflected in the relationship between the principal and the intermediary. States need to identify the alignment of interests at an early stage, or risk strategic failure. There are two ideal types of intermediaries—dealers and brokers. Case studies of the United States’ support to the Mujahideen in Afghanistan and to UNITA in Angola (channeled through Pakistan and Zaire, respectively) demonstrate that intermediaries affect the provision of external support. States engaging in counterterrorism need to look beyond sponsors of terrorism and explore the role of all states involved in the process of conflict delegation. That states use intermediaries when providing support to non-state armed groups indicates that holding states accountable for violating the nonintervention principle under international law should be reconsidered.