Ambiguity about whether a weapon is nuclear-armed prior to its launch is an underappreciated, serious, and growing danger. Rising geopolitical tensions and the decay of arms control are exacerbating the risk that such pre-launch warhead ambiguity could lead to nuclear use in a crisis or conflict. Recent developments in technology—as well as potential future advances, such as the development of ambiguous intercontinental missiles—further add to the danger.
A first step toward reducing these risks is to enhance awareness among decisionmakers of the causes and potential consequences of ambiguity. Unilateral and cooperative risk-mitigation measures could further reduce the danger of escalation, including in conflicts between the United States and Russia or the United States and China.