Historical and legal accounts of domestic military and militarized use abound, but there is no systematic normative treatment of the issue. This article argues that an important normative principle that governs domestic military use is that citizens ought not to be treated as enemies. Using examples drawn from the United States, it shows that apart from any instrumental considerations such as fears of military coups and excessive violence, domestic military use is prohibited in principle when it relates to citizens as enemies. To treat citizens as enemies undermines their standing as members of the state’s political community, and so violates governments’ duty to not commit expressive harms against them. This principle has implications for current dilemmas regarding domestic military use, as well as militarized domestic law enforcement. The latter gain the normative commitments of militaries as they militarize, and in so doing lose permissions to operate domestically.