The Carter Doctrine was a policy proclaimed by President of the United States Jimmy Carter in his State of the Union Address on January 23, 1980, which stated that the United States would use military force if necessary to defend its national interests in the Persian Gulf region. The doctrine was a response to the 1979 invasion of Afghanistan by the Soviet Union, and was intended to deter the Soviet Union—the Cold War adversary of the United States—from seeking hegemony in the Persian Gulf. After stating that Soviet troops in Afghanistan posed "a grave threat to the free movement of Middle East oil", Carter proclaimed: