This article examines how states signal alliance commitments, specifically regarding nuclear weapons.

Research Question: How effective are specific policies in signaling commitment?

Data & Methods: Analysis of a new dataset on foreign nuclear deployments (1950-2000).

Findings: Formal alliances with nuclear powers provide deterrence benefits; however, stationing additional weapons does not enhance credibility.

These findings challenge the notion that physical presence is necessary to communicate commitment in extended deterrence. The results highlight distinct signaling mechanisms of 'hand-tying' and 'sunk cost,' revealing their complex dynamics.