North Atlantic Treaty

The North Atlantic Treaty was signed in Washington by twelve countries: the United States, Canada, Britain, France, Italy, Belgium, the Netherlands, Luxembourg, Norway, Denmark, Iceland and Portugal. It created NATO, the military alliance whose central provision, Article 5, states that an armed attack against one member is to be considered an attack against all. The alliance was formed in response to Soviet pressure in Europe after the Czechoslovak coup and the Berlin Blockade of 1948. Greece and Turkey joined in 1952 and West Germany in 1955, and the Soviet bloc answered with the Warsaw Pact. Article 5 has been invoked once, after the September 11 attacks in 2001. After the Cold War NATO expanded eastward, and Finland and Sweden joined in 2023 and 2024.

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