The United States Department of State (DOS), or simply the State Department, is an executive department of the U.S. federal government responsible for the country's foreign policy and relations. Equivalent to the ministry of foreign affairs of other nations, its primary duties are advising the U.S. president on international relations, administering diplomatic missions, negotiating international treaties and agreements, and representing the U.S. at the United Nations. The department is headquartered in the Harry S Truman Building, a few blocks from the White House, in the Foggy Bottom neighborhood of Washington, D.C.; "Foggy Bottom" is thus sometimes used as a metonym.

The officially stated goals of the foreign policy of the United States of America, including all the bureaus and offices in the United States Department of State, as mentioned in the Foreign Policy Agenda of the Department of State, are "to build and sustain a more democratic, secure, and prosperous world for the benefit of the American people and the international community". Liberalism has been a key component of US foreign policy since its independence from Britain. Since the end of World War II, the United States has had a grand strategy which has been characterized as being oriented around primacy, "deep engagement", and/or liberal hegemony. This strategy entails that the United States maintains military predominance; builds and maintains an extensive network of allies ; integrates other states into US-designed international institutions ; and limits the spread of nuclear weapons.