The Institute of Medicine recently called for a tobacco-free military, citing evidence that high rates of tobacco use harm readiness and create enormous costs for the Department of Defense and the Veterans Administration. The pro-tobacco activities of the tobacco industry and others, sometimes supported by military authorities even when prohibited by policy, have created a culture highly hospitable to smoking. Through qualitative secondary analysis of data from interviews and focus groups, this article explores the reasons enlisted personnel and their supervisors, installation tobacco control managers, and service policy leaders give for why tobacco control policy change "cannot" effectively be achieved. Three primary reasons were given: policies would impinge on the "right to smoke," policies would be unenforceable and lead to disciplinary breakdown, and the rights of civilian workers on military installations precluded policy enforcement. Yet evidence suggests that these reasons are not only invalid, but inconsistent with military policies addressing other threats to the health of personnel. This pervasive tobacco "exceptionalism" is a significant barrier to achieving a tobacco-free military. The military, Congress, and the President should re-evaluate the "can'ts" that have prevented effective action, and act to regulate and eventually abolish tobacco use in the armed forces.