Entered into force August 24, 1949.
In accordance with Article 11, the Treaty was subject to ratification by the signatories. The Treaty entered into force between the states which had ratified it as soon as the ratifications of a majority of the signatories, including the ratifications of Belgium, Canada, France, Luxembourg, the Netherlands, the United Kingdom and the United States were deposited with the Government of the United States of America. In accordance with Article 10 of the Treaty, the Parties may, by unanimous consent, invite any other European state in a position to further the principles of this Treaty and to contribute to the security of the North Atlantic area to accede to the Treaty. Any state so invited may become a party to the Treaty by depositing its instrument of accession with the Government of the United States of America.