NATO Founded

In April 1949, twelve countries in North America and Western Europe signed the North Atlantic Treaty in Washington, creating the North Atlantic Treaty Organization. It was the first peacetime military alliance the United States had joined outside the Western Hemisphere, and it became the central institution of Western security through the Cold War and beyond. Its founding helped harden the division of Europe into two opposing blocs.

The alliance grew out of the instability that followed the Second World War. Much of Western Europe was economically shattered, and many governments feared both Soviet power and the strength of domestic communist parties in countries such as France and Italy. Soviet influence over Eastern Europe, the communist takeover in Czechoslovakia in early 1948, and the Berlin Blockade that began that summer deepened these anxieties. In March 1948, Britain, France, and the Benelux countries signed the Treaty of Brussels, a mutual defense pact, but they recognized that they could not balance Soviet strength without American involvement. Negotiations with the United States and Canada followed, helped by a 1948 Senate resolution that opened the way for American participation in such arrangements.

The resulting treaty was short. The founding members were the United States, Canada, Britain, France, Belgium, the Netherlands, Luxembourg, Italy, Portugal, Norway, Denmark, and Iceland. Its best-known provision, Article 5, states that an armed attack against one member is to be considered an attack against all. Notably, it does not require an automatic military response; each member is to take whatever action it deems necessary. Article 5 would be invoked only once, after the September 2001 attacks on the United States.

At first NATO was more a political guarantee than a unified military force. That changed after the outbreak of the Korean War in 1950, which heightened fears of a similar conflict in Europe. The alliance built an integrated command structure, and General Dwight Eisenhower became its first Supreme Allied Commander. Greece and Turkey joined in 1952, and West Germany in 1955. The Soviet Union responded that year by forming the Warsaw Pact with its Eastern European satellites, formalizing the two-bloc order.

NATO outlasted the Cold War it was created for. After 1991 it took on new roles, including peacekeeping in the Balkans, and it expanded to include former Warsaw Pact states and ex-Soviet republics. Supporters credit it with deterring war in Europe and binding former enemies together; critics, including many Russian leaders, argue that its enlargement has fueled mistrust. Its role remains a central question in European security debates.