The United States has an established structure of foreign relations. It is a permanent member of the United Nations Security Council, and New York City is home to the United Nations headquarters. It is also a member of the G7,[251] G20, and OECD. Almost all countries have embassies in Washington, D.C., and many have consulates around the country. Likewise, nearly all nations host American diplomatic missions. However, Iran, North Korea, Bhutan, and Taiwan do not have formal diplomatic relations with the United States (although the U.S. maintains unofficial relations with Taiwan and supplies it with military equipment).[252]
The United States has a "Special Relationship" with the United Kingdom[253] and strong ties with Canada,[254] Australia,[255] New Zealand,[256] the Philippines,[257] Japan,[258] South Korea,[259] Israel,[260] and several European Union countries, including France, Italy, Germany, Spain, and Poland.[261] It works closely with fellow NATO members on military and security issues and with its neighbors through the Organization of American States and free trade agreements such as the trilateral United States–Mexico–Canada Agreement. Colombia is traditionally considered by the United States as its most loyal ally in South America.[262][263]
The U.S. exercises full international defense authority and responsibility for Micronesia, the Marshall Islands and Palau through the Compact of Free Association.[264]