The history of the North Atlantic Treaty Organization (NATO) begins in the immediate aftermath of World War II. In 1947, the United Kingdom and France signed the Treaty of Dunkirk and the United States set out the Truman Doctrine, the former to defend against a potential German attack and the latter to counter Soviet expansion. The Treaty of Dunkirk was expanded in 1948 with the Treaty of Brussels to add the three Benelux countries (Belgium, the Netherlands, and Luxembourg) and committed them to collective defense against an armed attack for fifty years. The Truman Doctrine expanded in the same year, with support being pledged to oppose the communist rebellions in Greece and Czechoslovakia, as well as Soviet demands from Turkey. In 1949, the NATO defensive pact was signed by twelve countries on both sides of the North Atlantic – the five Brussels signatories, the United States, Canada, Italy, Portugal, Norway, Denmark, and Iceland. Greece and Turkey joined in 1952, West Germany joined in 1955, Spain joined in 1982, Czech Republic, Hungary and Poland joined in 1999, Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia, and Slovenia joined in 2004, Albania and Croatia joined in 2009, Montenegro joined in 2017, North Macedonia joined in 2020, Finland joined in 2023, and Sweden joined in 2024.
The structure of NATO evolved throughout the Cold War and its aftermath. The first headquarters were located at 13, Belgrave Square, London (1948-51), before moving to a more suitable space in Paris in April 1952. The NATO Military Command Structure was established in 1950, enhancing its defences for the longer term against potential Soviet attack. In April 1951, Allied Command Europe and its headquarters (Supreme Headquarters Allied Powers Europe) were established; later, four subordinate headquarters were added in Northern and Central Europe, the Southern Region, and the Mediterranean.
From the 1950s to 2003, the Strategic Commanders were the Supreme Allied Commander Europe (SACEUR) and the Supreme Allied Commander Atlantic (SACLANT).
Background
NATO has its roots in the Atlantic Charter, a 1941 agreement between the United States and United Kingdom. The Charter laid out a framework for international cooperation without territorial expansion after World War II.
The Treaty of Brussels was a mutual defense treaty against the Soviet threat at the start of the Cold War. It was signed on 17 March 1948 by Belgium, the Netherlands, Luxembourg, France, and the United Kingdom and was the precursor to NATO. The Soviet threat became immediate with the Berlin Blockade in 1948, leading to the creation of a multinational defense organization, the Western Union Defence Organisation, in September 1948. However, the parties were too weak militarily to counter the Soviet Armed Forces. In addition, the communist 1948 Czechoslovak coup d'état had overthrown a democratic government, and British foreign minister Ernest Bevin reiterated that the best way to prevent another Czechoslovakia was to evolve a joint Western military strategy. He got a receptive hearing in the United States, especially with the American anxiety over Italy and the Italian Communist Party.
1949–1991: Cold War
1949–1962: Beginnings
In 1948, European leaders met with US defense, military, and diplomatic officials at the Pentagon, exploring a framework for a new and unprecedented association. The talks resulted in the North Atlantic Treaty, and the United States signed on 4 April 1949. Participants included the five Treaty of Brussels states, as well as the United States, Canada, Portugal, Italy, Norway, Denmark and Iceland. The first NATO Secretary General, Lord Ismay, stated in 1949 that the organization's goal was "to keep the Russians out, the Americans in, and the Germans down". Popular support for the treaty was not unanimous, and some Icelanders participated in a pro-neutrality, anti-membership riot in March 1949. The formation of NATO can be seen as the primary institutional consequence of a school of thought called Atlanticism, which stressed the importance of trans-Atlantic cooperation.
The members agreed that an armed attack against any of them in Europe or North America would be considered an attack against them all. Consequently, they agreed that if an armed attack occurred, each of them, in the exercise of the right of individual or collective self-defense, would assist the member being attacked and take such action as it deemed necessary, including the use of armed force, to restore and maintain the security of the North Atlantic area. The treaty does not require members to respond with military action against an aggressor. Although obliged to respond, they maintain the freedom to choose the method by which they do so. That differs from Article IV of the Treaty of Brussels, which clearly states that the response is military in nature. NATO members are nonetheless assumed to aid the attacked member militarily. The treaty was later clarified to include both the members' territory and their "vessels, forces or aircraft" north of the Tropic of Cancer, including some overseas departments of France.
The creation of NATO brought about some standardization of allied military terminology, procedures, and technology, which, in many cases, meant European countries adopting US practices. Roughly 1300 Standardization Agreements (STANAG) codified many of the common practices that NATO has achieved. Thus many NATO countries introduced the 7.62×51mm NATO rifle cartridge in the 1950s as a standard firearm-cartridge. Fabrique Nationale de Herstal's FAL, which used the 7.62mm NATO cartridge, was adopted by 75 countries, including many outside NATO. Also, aircraft-marshaling signals were standardized so that any NATO aircraft could land at any NATO base. Other standards such as the NATO Stock Number became widespread, and the NATO phonetic alphabet extends beyond NATO into civilian use.
The outbreak of the Korean War in June 1950 proved crucial for NATO, as it raised the apparent threat of all Communist countries working together and forced the alliance to develop concrete military plans. NATO set up the Supreme Headquarters Allied Powers Europe (SHAPE) to direct forces in Europe; it began work under Supreme Allied Commander Dwight Eisenhower in January 1951. In September 1950, the NATO Military Committee called for an ambitious buildup of conventional forces to meet the Soviets and reaffirmed that position at the February 1952 meeting of the North Atlantic Council in Lisbon. The conference, seeking to provide the forces necessary for NATO's Long-Term Defence Plan, called for an expansion to 96 divisions. However, that requirement dropped the following year to roughly 35 divisions, with heavier use to be made of nuclear weapons. At this time, NATO could call on about 15 ready divisions in Central Europe and on another 10 in Italy and Scandinavia. Also at Lisbon, the post of Secretary General of NATO as the organization's chief civilian was created, and eventually the North Atlantic Council appointed Lord Ismay to the post.
In September 1952, the first major NATO maritime exercises began. Exercise Mainbrace brought together 200 ships and over 50,000 personnel to practice the defence of Denmark and Norway. Other major exercises that followed included: Exercise Grand Slam and Exercise Longstep, naval and amphibious exercises in the Mediterranean Sea; Italic Weld, a combined air-naval-ground exercise in northern Italy; Grand Repulse, involving the British Army on the Rhine (BAOR), the Netherlands Corps and Allied Air Forces Central Europe (AAFCE); Monte Carlo, a simulated atomic air-ground exercise involving the Central Army Group; and Weldfast, a combined amphibious landing exercise in the Mediterranean Sea involving American, British, Greek, Italian, and Turkish naval forces.
Greece and Turkey joined the alliance in 1952, which forced a series of controversial negotiations, mainly between United States and Britain, over how to bring both countries into the military command-structure. While that overt military preparation was going on, covert stay-behind arrangements initially made by the Western European Union to continue resistance after an expected Soviet invasion - including Operation Gladio - were transferred to NATO control. Ultimately, unofficial bonds began to grow between the respective armed forces of NATO member-states. Such links included the NATO Tiger Association (established in 1961) and competitions such as the Canadian Army Trophy for tank gunnery, instituted in 1963.
In 1954, the Soviet Union suggested that it might join NATO to preserve peace in Europe. The NATO countries, fearing that the Soviet Union's motive was to weaken the alliance, ultimately rejected that proposal. On 17 December 1954, the North Atlantic Council approved MC 48, a key document in the evolution of NATO nuclear thought. MC 48 emphasized that NATO had to use atomic weapons from the outset of a war with the Soviet Union, whether or not the Soviets chose to use them first. That gave SACEUR the same prerogatives for automatic use of nuclear weapons that existed for the commander-in-chief of the US Strategic Air Command.
The incorporation of West Germany into the organization on 9 May 1955 was described as "a decisive turning point in the history of our continent" by Halvard Lange, then the Norwegian Foreign Affairs Minister. The alliance saw German manpower as necessary to have enough conventional forces to resist a Soviet invasion. One of the immediate results of West German entry was the creation of the Warsaw Pact, which was signed on 14 May 1955 by the Soviet Union, Hungary, Czechoslovakia, Poland, Bulgaria, Romania, Albania, and East Germany, thereby delineating the two opposing sides of the Cold War in Europe.
Three major NATO exercises took place concurrently in the northern autumn of 1957. Operation Counter Punch, Operation Strikeback, and Operation Deep Water were together the most ambitious military undertaking for the alliance so far, involving more than 250,000 men, 300 ships, and 1,500 aircraft operating from Norway to Turkey.
Strained relations with France
NATO's unity was breached early in its history with a crisis occurring during Charles de Gaulle's presidency (1959–1969) of France. De Gaulle protested the strong role of the United States in NATO and what he perceived as a special relationship between it and the United Kingdom. In a memorandum sent to US president Dwight Eisenhower and British prime minister Harold Macmillan on 17 September 1958, he argued for the creation of a tripartite directorate, which would put France on an equal footing with the US and the UK.
Considering the response to be unsatisfactory, de Gaulle began constructing an independent defense-force for his country. General de Gaulle doubted that the United States would enter into a full-fledged war with the USSR in case of an aggression of the Warsaw Pact against Western Europe, especially after the USSR had acquired a balistic capability to hit targets in the continental United States with megaton-weapons, and might be tempted to wage a "limited" nuclear war in Western Europe and prevent NATO European allies having nuclear weapons to hit targets in the USSR. In February 1959, France withdrew its Mediterranean Fleet from NATO command, and it later banned the stationing of foreign nuclear weapons on French soil. That caused the United States to transfer 300 military aircraft out of France and to return control of the air-force bases that it had operated in France since 1950 to France by 1967.