<P> Nixon, who replaced Johnson in 1969, referred to his foreign policy as détente, a relaxation of tension . Although it continued to aim at restraining the Soviet Union, it was based on political realism, thinking in terms of national interest, as opposed to crusades against communism or for democracy . Emphasis was placed on talks with the Soviet Union concerning nuclear weapons called the Strategic Arms Limitation Talks . Nixon reduced U.S. military presence in Vietnam to the minimum required to contain communist advances, in a policy called Vietnamization . As the war continued, it grew less popular . A Democratic Congress forced Nixon, a Republican, to abandon the policy in 1973 by enacting the Case--Church Amendment, which ended U.S. military involvement in Vietnam and led to successful communist invasions of South Vietnam, Laos and Cambodia . </P> <P> President Jimmy Carter came to office in 1977 and was committed to a foreign policy that emphasized human rights . However, in response to the Soviet invasion of Afghanistan, containment was again made a priority . The wording of the Carter Doctrine (1980) intentionally echoeed that of the Truman Doctrine . </P> <Table> <Tr> <Td> </Td> <Td> This section needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (September 2017) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This section needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (September 2017) (Learn how and when to remove this template message) </Td> </Tr>

Where was the policy of containment first tested