A Break From 160 Years of Precedent
From George Washington's warning against "entangling alliances" through two world wars fought without a permanent peacetime commitment, the United States avoided binding military alliances outside the Western Hemisphere. NATO ended that tradition.
The North Atlantic Treaty Organization is a mutual-defense alliance created by the Washington Treaty of 1949. Its core commitment, Article 5, holds that an armed attack against one member in Europe or North America is treated as an attack against all of them.
NATO was built to deter Soviet expansion into Western Europe after World War II. More than three decades after the Cold War's end, it remains the most significant military alliance the United States belongs to, and has grown from 12 founding members to 32.