Citizenship in the United States
Military participation (if needed). Citizens do not have to serve in the United States military.  As of 2016, the United States has an all-volunteer military.  However, in the past, the United States has used "a draft" to call people up to serve as soldiers.  This has not happened since the Vietnam War.  Still, male United States citizens have to sign up with the Selective Service System so they could be called up if there were a draft in the future.