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NATO emblem

North Atlantic Treaty Organization

NATO provides unified military leadership for the common defense of 26 Western nations. It was established in 1950 by the North Atlantic Treaty, Article 5 of which provides that an armed attack against one or more member nations in Europe or North America shall be considered an attack against all members.

NATO has its headquarters in Brussels, Belgium. The official website is

Member Nations

European members of NATO

Belgium (1949)
Bulgaria (2004)
Canada (1949)
Czech Republic (1999)
Denmark (1949)
Estonia (2004)
France (1949)
Germany (1954)
Greece (1951)
Hungary (1999)
Iceland (1949)
Italy (1949)
Latvia (2004)
Lithuania (2004)
Luxembourg (1949)
Netherlands (1949)
Norway (1949)
Poland (1999)
Portugal (1949)
Romania (2004)
Slovakia (2004)
Slovenia (2004)
Spain (1982)
Turkey (1951)
United Kingdom (1949)
United States (1949)


NATO's highest authority is the North Atlantic Council, which is composed of permanent delegates from all members. The Council is responsible for general policy, budgetary outlines, and administrative actions, and is headed by a Secretary General nominated by member nations.

Secretary Generals of NATO
Lord Ismay, 1952-1957
Paul Henri Spaak, 1957-1961
Dirk U. Stikker, 1961-1964
Manlio Brosio, 1964-1971
Joseph Luns, 1971-1984
Lord Carrington, 1984-1988
Manfred Werner, 1988-1994
Willy Claes, 1994-1995
Javier Solana, 1995-1999
Lord Robertson, 1999-2003
Jaap de Hoop Scheffer, 2003-2009
Anders Fogh Rasmussen, 2009-2014
Jens Staltenberg, 2014-

Subordinate to the Council is the Secretariat, which handles all nonmilitary functions of the alliance.

Also directly responsible to the Council is the Military Committee, which establishes the military policy of NATO. The Council consists of the heads of member nations or their representatives. All decisions of the Council must be unanimous in order to be implemented.


In 1947, the United States and Great Britain signed the Dunkirk Treaty, in which each nation pledged to come to the aid of the other in case of aggression from the Soviet Union. That agreement was complemented in 1948, when Belgium, France, Great Britain, Luxembourg, and the Netherlands signed the Brussels Treaty, the goal of which was the collective defense of the signatory nations. Again the perceived threat was from the Soviet Union.

As the Soviet Union expanded its influence in Europe, the need for an even stronger alliance of Western nations became clear. That alliance was created by the North Atlantic Treaty, which was signed by twelve nations -- Belgium, Canada, Denmark, France, Great Britain, Iceland, Italy, Luxembourg, The Netherlands, Norway, Portugal, and the United States -- on April 4, 1949, in Washington, D.C.

In September 1950, members of the alliance formed the North Atlantic Treaty Organization, in response to the Communist invasion of South Korea.

Lieutenant General Hans Speidel (right), who had served as a General in the German Army during World War II, became a NATO commander in April 1957. His superior, French General Jean-Étienne Valluy is at his right.
Hans Speidel and Jean-Etienne Valluy

General Lauris Norstad (left), Supreme Allied Commander in Europe, and U.S. Senator Theodore Green, Chairman of the Senate Foreign Relations Committee, study a 1958 map of NATO.
1958 map of NATO

A U.S. aircraft carrier in the Mediterranean salutes NATO's tenth anniversary.
carrier salute

The permanent NATO headquarters building at Dauphine Gate near the Bois de Boulogne in Paris, France, neared completion in December 1959.
NATO headquarters

In 1967 NATO moved its headquarters from Paris, France, to Brussels, Belgium.

NATO was little more than a defensive alliance until 1997, when 30,000 NATO-led troops replaced a United Nations peacekeeping force in Bosnia, the first time NATO's military capabilities would be tested.

In March 1999, NATO went on the offensive, launching an aerial assault on Yugoslavia in order to weaken the regime of President Slobodan Milosevic and stop his campaign of genocide against Kosovo's Albanian population.

Another NATO-led peacekeeping force was sent into the Balkans in the summer of 2001 to enforce a peace agreement between groups representing ethnic Albanians and Slavs in Macedonia. NATO troops were replaced by European Union troops in 2003.

The Article 5 provision of the NATO treaty was invoked for the first time in history in response to the September 11, 2001, attacks on the World Trade Center and Pentagon -- several NATO members sent troops to fight alongside U.S. forces in Afghanistan, which the United States believed was harboring the terrorists who had masterminded the attacks.

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This page was last updated on 12/09/2018.