The United States Pacific Command (USPACOM) Area of Responsibility (AOR) encompasses about half the earth's surface, stretching from the waters off the west coast of the U.S. to the western border of India, and from Antarctica to the North Pole. There are few regions as culturally, socially, economically, and geo-politically diverse as the Asia-Pacific. The 36 nations that comprise the Asia-Pacific region are home to more than 50% of the world's population, three thousand different languages, several of the world's largest militaries, and five nations allied with the U.S. through mutual defense treaties. USPACOM is one of six geographic Unified Combatant Commands of the United States Armed Forces. Commander, U.S. Pacific Command (CDRUSPACOM) is the senior U.S. military authority in the Pacific Command AOR. CDRUSPACOM reports to the President of the United States through the Secretary of Defense and is supported by four component commands: U.S. Pacific Fleet, U.S. Pacific Air Forces, U.S. Army Pacific, and U.S. Marine Forces, Pacific. These commands are headquartered in Hawaii and have forces stationed and deployed throughout the region.