North Atlantic Treaty

4:30 p.m. in the Departmental Auditorium

At 4:30 p.m. on 4 April 1949, representatives of Belgium, Canada, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal, the United Kingdom and the United States met in Washington's Departmental Auditorium for the signing ceremony.

The twelve foreign ministers signed the North Atlantic Treaty. Secretary of State Dean Acheson signed for the United States while President Harry S. Truman stood beside him and described the pact as a shield against aggression.

The Marine Band's selections included "I Got Plenty of Nothing" and "It Ain't Necessarily So," prompting jokes at the ceremony.

What Article 5 actually promises

The signatories accepted a collective-defence formula under which an armed attack on one would be considered an attack on all — but each party would take the action it individually deemed necessary, potentially including armed force. It promises neither an automatic declaration of war nor identical military action by every ally.

Article 9 created a North Atlantic Council empowered to establish subsidiary bodies. The treaty did not itself set up the integrated military command structure that developed afterward.

Not binding until August

The signatures did not put the treaty into force that day. It became effective only after ratification by all twelve signatories, on 24 August 1949.

Article 14 designated the United States as depositary, which is why the original document sits in US government archives. After fifteen months of negotiation, the drafters Theodore Achilles and John Hickerson left the ceremony for bourbons in the basement bar of the old Willard Hotel.