© 2020, © 2020 Informa UK Limited, trading as Taylor & Francis Group. While the US obtained control of the seas in maritime East Asia after the dissolution of the Japanese empire in 1945, the Truman administration did not link its international security with maritime space in the immediate post-war period. The outbreak of the Korean War and the First Taiwan Strait Crisis drove the US to rethink the significance of international waters and gradually adopt a sea-oriented strategic command. This development altered the defence structure in Cold War East Asia and such perimeters of maritime defence remained in place until the US ended official relations with Taiwan in 1979.