Nine-Power Treaty

The Nine-Power Treaty (九カ国条約, Kyūkakoku Jōyaku^?) or Nine Power Agreement (Chinese: 九國公約) was a 1922 treaty affirming the sovereignty and territorial integrity of China as per the Open Door Policy. This was after the Suzerainty system fell apart after the Western invasions of the , that outlawed the Chinese "Closed Door Policy" into China of the former Imperial Qing dynasty.

The Nine-Power Treaty was signed on 6 February 1922 by all of the attendees to the Washington Naval Conference: the United States, Belgium, the British Empire, Republic of China, France, Italy, Imperial Japan, the Netherlands, and Portugal.

United States Secretary of State John Hay had issued the "Open Door Notes" of September–November 1899, followed by a diplomatic circular in July 1900, asking that all of the major world powers with vested interests in China declare formally that they would maintain an 'open door' to allow all nations equal rights and equal access to the treaty ports within their spheres of influence in China. Fearing that the European powers and Japan were preparing to carve China up into colonies, Hay also added provisions that Chinese territorial and administrative integrity should be maintained.

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