When the United States resumed diplomatic relations with the Soviet Union in 1933, Bohlen became one of three Russian-language officers in the Moscow embassy. After further assignments in Washington and Tokyo, in 1942 he became assistant chief of the Russian Section of the State Department's Division of European Affairs and in 1944 its chief. He attended the Moscow Conference of Foreign Ministers in 1943 and the Tehran and Yalta summits of the Allied leaders in 1944 and 1945.
Although later criticized by Senator Joseph McCarthy for his acquiescence in the decisions at Yalta, Bohlen in fact had reservations as to the wisdom of American policies. Like Kennan, he was deeply suspicious of Soviet actions and intentions. Unlike Kennan, who originally recommended acquiescence in the creation of a Soviet sphere of influence, Bohlen advocated firm diplomatic pressure to attempt to win Soviet concessions. Appointed political advisor to the secretary of state in 1946 and counselor to the Department of State in 1947, he helped develop the Cold War containment policy.
In 1953 Bohlen was appointed ambassador to the Soviet Union. McCarthyite attacks on his record held up his appointment until Secretary of State John Foster Dulles, while denying that Bohlen was a security risk, pledged that Bohlen would have little input in the secretary's policies. During 1957–1959 Bohlen was ambassador to the Philippines.
In 1959 Bohlen became special assistant to Secretary of State Christian A. Herter. Preparing for the June 1960 Soviet-American Paris summit, Bohlen advised President Dwight D. Eisenhower to remain resolute over West Berlin, then under considerable Soviet pressure. Bohlen accompanied Eisenhower to this meeting, which was cut short by the U-2 Crisis.
In their first eighteen months in office, President John F. Kennedy and Secretary of State Dean Rusk relied heavily on Bohlen's expertise. During the Cuban Missile Crisis, Bohlen counseled a mix of firmness and restraint and recommended a naval blockade of the island. He next served as ambassador to France during 1962–1967.
Appointed deputy undersecretary of state for political affairs in 1967, Bohlen called for the expansion of American trade with the Soviet bloc as a way to weaken Soviet control over Eastern Europe. He failed to anticipate the Soviet military intervention in Czechoslovakia in August 1968 but advised that, given Soviet determination to maintain its hold over Eastern Europe, the United States should restrict its response to diplomatic protests.
Bohlen retired in 1969, warning President Richard M. Nixon not to try using China against the Soviet Union. Bohlen was publicly skeptical of both the emerging American policy of détente and West German Chancellor Willy Brandt's Ostpolitik opening to East Germany. In retirement Bohlen became president of the investment company Italamerica, wrote his memoirs, and lectured extensively. He died in Washington, D.C., on 1 January 1974.
Isaacson, Walter, and Evan Thomas. The Wise Men: Six Friends and the World They Made; Acheson, Bohlen, Harriman, Kennan, Lovett, McCloy. New York: Simon and Schuster, 1986.; Ruddy, T. Michael. The Cautious Diplomat: Charles E. Bohlen and the Soviet Union, 1929–1969. Kent, OH: Kent State University Press, 1986.