Theories of crisis bargaining suggest that military mobilizations act as costly signals of resolve, increasing the credibility of coercive threats. In this article, I argue that air mobilizations, as a subset of military signals, demonstrate a lack of resolve during coercive bargaining for four reasons: they cost less in terms of human and financial resources (sunk costs), generate lower political costs (hand-tying), do not raise the risks of engagement (manipulation of risk), and do not significantly shift the balance of power—all compared with other military signals. Using new data that disaggregates military demonstrations into air, naval, and land signals during 210 cases of compellence, this article presents systematic evidence that air signals decrease the probability of coercive threat success compared with the alternatives. This finding holds important implications for theoretical and policy debates regarding the role of costly signals in international bargaining.