section: Soviet spies
question: What was the name of the head of the Counter Intelligence Branch of the Western Defense Command?
article: Manhattan Project
candidates: The prospect of sabotage was always present, and sometimes suspected when there were equipment failures. While there were some problems believed to be the result of careless or disgruntled employees, there were no confirmed instances of Axis-instigated sabotage. However, on 10 March 1945, a Japanese fire balloon struck a power line, and the resulting power surge caused the three reactors at Hanford to be temporarily shut down. With so many people involved, security was a difficult task. A special Counter Intelligence Corps detachment was formed to handle the project's security issues. By 1943, it was clear that the Soviet Union was attempting to penetrate the project. Lieutenant Colonel Boris T. Pash, the head of the Counter Intelligence Branch of the Western Defense Command, investigated suspected Soviet espionage at the Radiation Laboratory in Berkeley. Oppenheimer informed Pash that he had been approached by a fellow professor at Berkeley, Haakon Chevalier, about passing information to the Soviet Union. The most successful Soviet spy was Klaus Fuchs, a member of the British Mission who played an important part at Los Alamos. The 1950 revelation of Fuchs' espionage activities damaged the United States' nuclear cooperation with Britain and Canada. Subsequently, other instances of espionage were uncovered, leading to the arrest of Harry Gold, David Greenglass and Ethel and Julius Rosenberg. Other spies like George Koval and Theodore Hall remained unknown for decades. The value of the espionage is difficult to quantify, as the principal constraint on the Soviet atomic bomb project was a shortage of uranium ore. The consensus is that espionage saved the Soviets one or two years of effort.