There is a growing risk that the United States and its allies could face scenarios in which one or more adversaries might resort to nuclear weapons use in a regional conflict. In response to these growing risks, U.S. decisionmakers are revisiting the concept of intra-war deterrence, which is about influencing enemy actions during an ongoing conflict. The risks of deterrence failure have been a focal point in the testimony of recent U.S. Strategic Command (STRATCOM) commanders, including General Anthony Cotton, who said, “We must be ready if deterrence fails” in testimony in February 2024.

To assist in this thinking and to develop actionable insights for the U.S. policy and strategy communities, the Project on Nuclear Issues (PONI) invited a group of experts to develop competing strategies for responding to strategic deterrence failure. The project’s current contributors were each asked to respond to a scenario involving near-simultaneous battlefield nuclear use by Russia and China. The strategies focused on four specific themes: strategic objectives, assurance to allies, military responses, and non-kinetic responses. The strategies demonstrate agreement on key issues, such as the importance of deterring conventional aggression and the relevance of non-kinetic responses to adversary nuclear use. But the strategies also highlight important areas of disagreement about the relative importance and feasibility of assuring allies, at least relative to other strategic objectives; the advisability of a nuclear versus conventional response to deterrence failure; and what “winning” in a strategic deterrence failure scenario would look like.