Why Was NATO Formed?

The North Atlantic Treaty Organization (NATO) was founded on April 4, 1949, in Washington, D.C., when 12 North American and Western European countries signed the North Atlantic Treaty.

The instability that followed World War II drove the creation of NATO in 1949. Much of Europe was physically devastated and politically fragile. Western leaders feared communist expansion as the Soviet Union consolidated control over Eastern Europe and supported communist movements elsewhere. 

According to the Imperial War Museum, growing conflicts between the U.S. and the USSR over the spread of communism, competing policies such as America’s Marshall Plan and the Soviets’ Cominform as well as rising tensions over Germany, including the Berlin Blockade, convinced Western nations that collective security was necessary.

At the time of the organization's founding, the 12 member nations included Belgium, the United Kingdom, Canada, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal and the United States. 

NATO’s purpose was broader than simply opposing the Soviet Union. According to NATO’s official history, the alliance was built around three core goals: “deterring Soviet expansionism, forbidding the revival of nationalist militarism in Europe through a strong North American presence on the continent, and encouraging European political integration.”

Although President Harry S. Truman’s signing of the Economic Recovery Act of 1948, known as the Marshall Plan, provided funding for European recovery, countries still needed political and military organization for security, defense and strategic planning.

When U.S. Secretary of State Dean Acheson signed the treaty, it marked a major shift in American foreign policy, linking U.S. security to European nations. The treaty’s most well-known element, Article 5, established that “an armed attack against one or more of them… shall be considered an attack against them all.”

The USSR’s first nuclear weapon test in 1949 and the start of the Korean War in 1950 pushed NATO to build a formal, unified military system. The Allied Command Europe launched in 1951, led by U.S. General Dwight D. Eisenhower, with its Supreme Headquarters Allied Powers Europe, aka SHAPE, stationed near Paris (now located in Belgium). The following year, NATO activated the Allied Command Atlantic in Norfolk, Virginia. The commands continue to plan and execute all NATO military operations. 

More allies joined NATO in the 1950s, including Greece, Turkey and West Germany. The Soviet Union responded with the Warsaw Pact in 1955, a military alliance between the USSR and its Eastern European satellites. Today, 32 countries are members of NATO. Membership, according to Article 10 of the treaty, is open to any “European State in a position to further the principles of this Treaty and to contribute to the security of the North Atlantic area.”