In 1953 Dulles became the fifth DCI under President Eisenhower. His brother John Foster Dulles was Eisenhower's Secretary of State. Under the DDP Helms was specifically tasked in the defense of the agency against the threatened attack by Senator Joseph McCarthy, and also in the development of "truth serum" and other "mind control" drugs per the CIA's controversial Project MKUltra. From Washington, Helms oversaw the Berlin Tunnel, the 1953–1954 espionage operation which later made newspaper headlines. Regarding CIA activity, Helms considered information obtained by espionage to be more beneficial in the long run than the more strategically risky work involved in covert operations, which could backfire politically. Under his superior and mentor the DDP Wisner, the CIA marshaled such covert operations, which resulted in regime change in Iran in 1953 and Guatemala in 1954 and interference in the Congo in 1960. During the crises in Suez and Hungary in 1956 the DDP Wisner became distraught by what he saw as the disloyalty of allies and the loss of a precious cold-war opportunity. Wisner left in 1958. Passing over Helms, DCI Dulles appointed his rival Richard Bissell as the new DDP, who had managed the U-2 spy plane.