A majority of the world’s nations have militaries, and only 36 nations do not have a military. Many nations have mandatory military service. The United States has the highest military spending of any nation. Its military spending includes all of the Department of Defense’s regular activities, war spending, the nuclear weapon program, international military assistance, and other Pentagon-related spending. In 2020, the U.S. spent $778 billion on military spending, more than the next nine top-spending countries combined.