Grown or Built? Interests that Defend Commitments after 1945

When a security commitment is defended by an organised interest, the interest may have preceded the commitment, grown out of it, or been built on purpose by its sponsor. These three readings come from interest-group research, policy-feedback research and research on designing policies to last, and are rarely set side by side. We make them testable and apply them to attempts to end security commitments in the United States and Europe after 1945. The dependent variable is the survival of a commitment under an attempt to reverse it, not the level of spending. In the United States cases (the B-1 bomber, the F-22 and C-17, the F136 alternate engine, the closure of military bases, and all programmes proposed for termination in 2009), the breadth of a programme's supplier spread does not decide its survival: the F-22 and the C-17, with suppliers in 44 and 43 states, had opposite fates in 2009. Three findings follow. The legislature's own record can be the defending interest: programmes Congress had created or restored against the executive survived where programmes it had merely funded did not. Executive pressure can be graded from the Statements of Administration Policy: the only unconditional veto threat ended its programme, while conditional threats and objections did not end programmes Congress owned. And what protects a commitment is whether its central defenders can be compensated, down to the production site. In Europe, as the European Defence Fund's rules are rewritten, the veto member states wrote for themselves is extended while the Commission's rule for spreading benefits is made optional. We register one prediction on the Fund's successor. The evidence extends to material published on 1 November 2026, including reporting on member-state divisions over the European Competitiveness Fund.