The U.S.-Japan Security Alliance is a mutual defense agreement between the United States and Japan, established in 1960. It aims to ensure the security of both nations and promote stability in the Asia-Pacific region. Under this alliance, the U.S. maintains military bases in Japan, providing a strategic presence in the area. The alliance is based on the principle that an armed attack against Japan is considered an attack against the U.S. This partnership has evolved to address various security challenges, including regional threats and natural disasters, reinforcing cooperation in defense and humanitarian efforts.