The North Atlantic Treaty Organization (NATO, French: Organisation du traité de l'Atlantique nord), or North Atlantic Alliance, the Atlantic Alliance, the Western Alliance, is a military alliance. It was established by the North Atlantic Treaty in 1949 and it was signed in Washington, DC, United States, on April 4, 1949. Its headquarters are in Brussels, Belgium. Its other official name means the same in French: Organisation du traité de l'Atlantique nord (OTAN).

Languages 
NATO has two official languages, English and French, as defined in Article 14 of the North Atlantic Treaty.

History 
Its members in 1949 were the United States, Belgium, the Netherlands, Luxembourg, France, the United Kingdom, Canada, Portugal, Italy, Norway, Denmark and Iceland. On 18 February 1952, Greece and Turkey also joined.
 
When West Germany joined the organization on 9 May 1955 it was described as "a decisive turning point in the history of our continent" by Halvard Lange, Foreign Minister of Norway at the time., the result was the Warsaw Pact, signed on 14 May 1955 by the Soviet Union and its satellite states as response to NATO.

After the Cold War in 1999 three former communist countries, Hungary, the Czech Republic, and Poland joined NATO. On 29 March 2004 seven more Northern European and Eastern European countries joined NATO: Estonia, Latvia and Lithuania and also Slovenia, Slovakia, Bulgaria, and Romania.

Croatia and Albania received NATO membership invitation on 3 April 2008. The Republic of Macedonia received the only conditional invitation because it was vetoed by Greece because of its name dispute with Greece.

Montenegro joined on 5 June 2017.   Having changed its name to end the dispute,
North Macedonia joined NATO on 27 March 2020 and became its 30th member.
Ireland officially joined NATO on 8 September 2020 as an observer.

Apart from this, Iceland also threatened to leave during the Cod Wars, which would put the UK at fault, and NATO would lose a key position in the North Atlantic. They did not leave as they won the Cod Wars.

Related pages
 United Nations

Further reading 
 Asmus, Ronald D. Opening NATO's Door: How the Alliance Remade Itself for a New Era Columbia U. Press, 2002. 372 pp.
 Bacevich, Andrew J. and Cohen, Eliot A. War over Kosovo: Politics and Strategy in a Global Age. Columbia U. Press, 2002. 223 pp. 
 Eisenhower, Dwight D. The Papers of Dwight David Eisenhower. Vols. 12 and 13: NATO and the Campaign of 1952: Louis Galambos et al., ed. Johns Hopkins U. Press, 1989. 1707 pp. in 2 vol.
 Daclon, Corrado Maria Security through Science: Interview with Jean Fournet, Assistant Secretary-General of NATO, Analisi Difesa, 2004. no. 42
 Ganser, Daniele Natos Secret Armies: Operation Gladio and Terrorism in Western Europe,  
 Gearson, John and Schake, Kori, ed. The Berlin Wall Crisis: Perspectives on Cold War Alliances Palgrave Macmillan, 2002. 209 pp. 
 Gheciu, Alexandra. NATO in the 'New Europe''' Stanford University Press, 2005. 345 pp.
 Hendrickson, Ryan C. Diplomacy and War at NATO: The Secretary-General and Military Action After the Cold War Univ. of Missouri Press, 2006. 175 pp. 
 Hunter, Robert. "The European Security and Defense Policy: NATO's Companion - Or Competitor?" RAND National Security Research Division, 2002. 206 pp.
 Jordan, Robert S. Norstad: Cold War NATO Supreme Commander - Airman, Strategist, Diplomat St. Martin's Press, 2000. 350 pp. 
 Kaplan, Lawrence S. The Long Entanglement: NATO's First Fifty Years. Praeger, 1999. 262 pp. 
 Kaplan, Lawrence S. NATO Divided, NATO United: The Evolution of an Alliance. Praeger, 2004. 165 pp. 
 Kaplan, Lawrence S., ed. American Historians and the Atlantic Alliance. Kent State U. Press, 1991. 192 pp. 
 Lambeth, Benjamin S. NATO's Air War in Kosovo: A Strategic and Operational Assessment Santa Monica, Calif.: RAND, 2001. 250 pp. 
 Létourneau, Paul. Le Canada et l'OTAN après 40 ans, 1949–1989 Quebec: Cen. Québécois de Relations Int., 1992. 217 pp. 
 Maloney, Sean M. Securing Command of the Sea: NATO Naval Planning, 1948–1954. Naval Institute Press, 1995. 276 pp. 
 John C. Milloy. North Atlantic Treaty Organisation, 1948–1957: Community or Alliance? (2006), focus on non-military issues
 Powaski, Ronald E. The Entangling Alliance: The United States and European Security, 1950–1993. Greenwood, 1994. 261 pp. 
 Ruane, Kevin. The Rise and Fall of the European Defense Community: Anglo-American Relations and the Crisis of European Defense, 1950–55 Palgrave, 2000. 252 pp. 
 Sandler, Todd and Hartley, Keith. The Political Economy of NATO: Past, Present, and into the 21st Century. Cambridge U. Press, 1999. 292 pp. 
 Smith, Jean Edward, and Canby, Steven L.The Evolution of NATO with Four Plausible Threat Scenarios. Canada Department of Defense: Ottawa, 1987. 117 pp.
 Smith, Joseph, ed. The Origins of NATO Exeter, UK U. of Exeter Press, 1990. 173 pp. 
 Telo, António José. Portugal e a NATO: O Reencontro da Tradiçoa Atlântica  Lisbon: Cosmos, 1996. 374 pp. 
 Zorgbibe, Charles. Histoire de l'OTAN'' Brussels: Complexe, 2002. 283 pp.

References

Other websites 

 NATO Official Website
 Basic NATO Documents

1949 establishments