Abstract: This report focuses on the concept of “foreign terrorist fighters” (FTFs) as it relates to U.N. Security Council practice and principled humanitarian action in situations of armed conflict involving terrorists. It has two goals. First, we aim to provide a primer on the most salient issues at the intersection of counterterrorism measures and humanitarian aid and assistance, with a focus on the ascendant FTF framing. Second, we seek to put forward, for critical feedback and assessment, a provisional methodology for evaluating the following question: is it feasible to subject two key contemporary wartime concerns—the fight against FTFs and supporting humanitarian aid and assistance for civilians in terrorist-controlled territories—to meaningful empirical analysis?