Engage or isolate? This is the national security question that will drive the United States’ response to near-peer competitors like China and Russia, destabilizing middle powers like Iran and North Korea, and even the relatively powerless Cuba. Consistent engagement, even with adversary states, is beneficial. It can help avoid miscalculations, improve U.S. ability to clarify intentions, and decipher ambiguous signals. It also can increase understanding of adversary motivations and interests, which facilitates negotiation and potential development of conflict off-ramps. Conversely, isolation can limit adversaries’ options, negatively feed their fears, and wound their pride—obstructing alternative, preferred paths.