The North Atlantic Treaty Organization (OTNA) is an international military organization founded in 1949 under the North Atlantic Treaty Organization ( NATO ). Signed in Washington on April 4, 1949 . NATO is a collective defense system in which member states agree on mutual defense in response to any attack by external parties. Three NATO members (the United States, France and the United Kingdom ) are permanent members of the UN Security Council with veto power and are officially nuclear-weapon states . NATO is headquartered in Haren, Brussels , Belgium , while NATO headquarters is located near Mons , Belgium .

NATO or NATO is an international military alliance of 29 independent member countries throughout North America and Europe. Another 21 countries are participating in the NATO Partnership for Peace program, with 15 more participating in institutional dialogue programs.