Acheson Declaration

Also called: Acheson Line, Acheson speech

US Secretary of State Dean Acheson announced America's Pacific defense perimeter, leaving Korea and Taiwan outside it.

On 12 January 1950, in a speech at the National Press Club in Washington, Secretary of State Dean Acheson described the US defense perimeter in the Far East as running from the Aleutians through Japan and Okinawa to the Philippines. Korea and Taiwan lay outside it. US troops had already left South Korea in June 1949, leaving only a military advisory group.

The speech is counted as one of the reasons North Korea judged that the US would not intervene and prepared its invasion. When the North invaded in June 1950, the US entered the war at once through the United Nations.