Since the end of World War II, the United States has been at war (overtly or covertly) with at least 23 countries. A partial list of our historical adversaries, from In These Times (Nov. 26, 2001):
China, Korea, Guatemala, Indonesia, Cuba, Belgian Congo, Peru, Laos, Vietnam, Cambodia, Grenada, Libya, El Salvador, Nicaragua, Panama, Iraq, Sudan, Yugoslavia, Dominican Republic, Laos, Iran, Chile, Somalia, Afghanistan.