In Japan, the Japan Self-Defense Force (JSDF) has a range of missions, including territorial defense, monitoring the country’s air and maritime spaces, countering piracy and terrorism, and conducting humanitarian operations; the JSDF exercises regularly with the US military and increasingly with other regional countries, including Australia and the Philippines

Japan’s alliance with the US is one of the cornerstones of the country’s security, as well as a large component of the US security posture in Asia; the US-Japan mutual defense treaty grants the US the right to base US military forces in Japan, including aircraft and ships, in return for US security guarantees; the Japanese Government provides approximately $3 billion on average per year to offset the cost of stationing US forces in Japan; in addition, it pays compensation to localities hosting US troops, rent for bases, and costs for new facilities to support the US presence; Japan also has Major Non-NATO Ally (MNNA) status with the US, a designation under US law that provides foreign partners with certain benefits in the areas of defense trade and security cooperation

Japan was disarmed after its defeat in World War II; shortly after the Korean War began in 1950, US occupation forces in Japan created a 75,000-member lightly armed force called the National Police Reserve; the JSDF was founded in 1954; Article 9 of Japan’s 1947 constitution renounced the use of force as a means of settling international disputes; however, Japan has interpreted Article 9 to mean that it can maintain a military for national defense purposes and, since 1991, has allowed the JSDF to participate in noncombat roles overseas in a number of UN peacekeeping missions and in the US-led coalition in Iraq; in 2014-2015, the Japanese Government reinterpreted the constitution as allowing for "collective self-defense," described as the use of force on others’ behalf if Japan’s security was threatened; in 2022, the government released security policy documents that declared Japan’s intention to develop "counterstrike” capabilities, including armed drones and cruise missiles, and outlined plans to increase Japan’s security-related expenditures to 2% of GDP (2025)