North Atlantic Treaty Organization
Flag of NATO.svg
Flag of NATO
North Atlantic Treaty Organization (orthographic projection).svg
Formation 4 April 1949
Type Military Alliance
Headquarters Brussels, Belgium
Membership Member states

The North Atlantic Treaty Organization or NATO is an intergovernmental military alliance based on the North Atlantic Treaty which was signed on 4 April 1949. The NATO headquarters are in Brussels, Belgium, and the organization constitutes a system of collective defence whereby its member states agree to mutual defense in response to an attack by any external party. For its first few years, NATO was not much more than a political association. However, the Korean War galvanized the member states, and an integrated military structure was built up under the direction of two U.S. supreme commanders. The first NATO Secretary General, Lord Ismay, famously stated the organization's goal was "to keep the Russians out, the Americans in, and the Germans down". Doubts over the strength of the relationship between the European states and the United States ebbed and flowed, along with doubts over the credibility of the NATO defence against a prospective Soviet invasion—doubts that led to the development of the independent French nuclear deterrent and the withdrawal of the French from NATO's military structure in 1966. After the fall of the Soviet Union and the rise of the Russian Federation, the Russian Federation began to re-establish relations with NATO, and talks over an military defense are under way, but keep coming to a halt when Russia intervenes. NATO is currently competing with PITO, a pact led by India and China.