Clifford became an early supporter of the containment strategy. He and presidential aide George M. Elsey drafted a memorandum on Soviet-American relations that urged the Western powers to ally against further Soviet expansion. Clifford was largely responsible for drafting Truman's February 1947 speech that outlined the Truman Doctrine and was a major architect of the 1947 National Security Act.
Clifford contributed to drafting the European Recovery Act of 1948 that put the Marshall Plan into effect and to the establishment of the 1949 North Atlantic Treaty. In 1948 he helped persuade Truman to recognize the new state of Israel. Clifford was one of the planners of the 1949 Point Four Program, whereby Truman promised substantial economic aid to underdeveloped countries.
In early 1950 Clifford left the White House to practice law in Washington, D.C. By 1960 he was widely considered the city's most influential Democratic lawyer. After handling several legal matters for then Senator John F. Kennedy, in late 1960 Clifford headed the president-elect's transition team but refused any formal office. Both Kennedy and his successor, Lyndon B. Johnson, however, called upon Clifford for advice on various matters. After the Bay of Pigs fiasco of April 1961, Clifford advised Kennedy to set up an independent oversight body to supervise the intelligence community. Kennedy then appointed Clifford to the new Foreign Intelligence Advisory Board, of which he became chairman in 1963.
In the early 1960s Clifford did not oppose the initial commitment of U.S. aid to South Vietnam. Together with Under-secretary of State George W. Ball, however, Clifford strongly opposed the major May 1965 deployment of American ground forces in Vietnam. Having lost this argument, Clifford believed that the United States should prosecute the war vigorously.
In late January 1968, Clifford was confirmed as secretary of defense, replacing the conflicted Robert S. McNamara for Johnson's final nine months as president. Clifford set up a Vietnam Task Force to reassess the situation in Vietnam and soon realized that the U.S. military had no concrete plan for victory. In early March 1969, he therefore recommended to the president that the United States commit only those forces necessary to meet immediate needs in Vietnam.
Fearing that victory was unattainable, Clifford summoned another meeting of the so-called Wise Men, most of whom concluded that the United States could not attain its ends in Vietnam and should begin peace negotiations. This contributed to Johnson's public announcement on 31 March 1968 of a unilateral bombing halt and to his decision not to seek the presidency again. Throughout 1968 Clifford battled administration hawks, most notably National Security Advisor Walt W. Rostow and former Secretary of State Dean Rusk, to maintain the bombing halt and continue negotiations with North Vietnam while publicly exerting pressure on South Vietnamese officials to join in peace talks.
In the early months of Richard Nixon's administration, Clifford praised the new president's intention to withdraw American troops. But Clifford alienated both Nixon and Johnson in the summer of 1969 when he publicly urged the unilateral withdrawal of 100,000 American troops by December 1969 and of all ground forces by December 1970. He also condemned the May 1970 U.S. invasion of Cambodia.
Clifford continued to practice law in Washington and play the role of Democratic Party elder statesman. Under President Jimmy Carter, Clifford undertook diplomatic assignments to Greece, Turkey, Cyprus, India, and Pakistan and helped to win Senate ratification of the Panama Canal Treaties. Although he avoided prosecution, in the late 1980s and early 1990s Clifford's involvement with the Bank of Credit and Commerce International, which lost billions of dollars in fraudulent dealings, besmirched his reputation, as did his well-publicized negligence as trustee to the family holdings of deceased elder statesman W. Averell Harriman. Clifford died in Bethesda, Maryland, on 10 October 1998.
Berman, Larry. Lyndon Johnson's War: The Road to Stalemate in Vietnam. New York: Norton, 1989.; Clifford, Clark, with David Holbrooke. Counsel to the President: A Memoir. New York: Random House, 1991.; Frantz, Douglas, and David McKean. Friends in High Places: The Rise and Fall of Clark Clifford. Boston: Little, Brown, 1995.; Herring, George C. Lyndon Johnson and Vietnam: A Different Kind of War. Austin: University of Texas Press, 1994.