Donald Maclean (spy) - Washington

Washington

Then they moved to Washington, D.C., where Maclean did his most valuable spying work as First Secretary at the British embassy from 1944 to 1948. In the latter period he acted as Secretary of the Combined Policy Committee on Atomic Development.

He was Joseph Stalin's main source of information about communications and policy development between Winston Churchill and Franklin D. Roosevelt, and then between Churchill or Clement Attlee and Harry S. Truman. Although Maclean did not transmit technical data on the atom bomb, he reported on its development and progress, particularly the amount of plutonium (used in the Fat Man bombs) available to the United States. As the British representative on the American-British-Canadian Council on the sharing of atomic secrets, he was able to provide the Soviet Union with information from Council meetings. This gave Soviet scientists the ability to predict the number of bombs that could be built by the Americans. Coupled with the efforts of Los Alamos-based scientists Alan Nunn May, Klaus Fuchs and Theodore Hall (who had been identified but was allowed to remain at large), Maclean's reports to his NKVD controller gave the Soviets a basis to estimate their nuclear arsenal's relative strength against that of the United States and Britain.

The author S.J. Hamrick (alias W.T. Tyler a Foreign Service officer) claims that Philby played a crucial role in a 1949-1950 British disinformation campaign to mislead the Soviets about Anglo-American nuclear capacities and willingness to retaliate against a Soviet invasion of Western Europe. While he admits he cannot prove his thesis beyond all doubt—by definition, so ingenious a scheme would never have left a paper trail—his circumstantial evidence taken from a careful reading of the Venona Intercepts explains much in the public domain that is otherwise is a conundrum.

If there were such a campaign, Maclean may have been working with Philby on this scheme and inflating the amounts of plutonium rather than providing accurate figures. Stalin doubted that the United States would start a nuclear war against the Soviet Bloc over minor aggressions like the Berlin Blockade or arming North Korea and North Vietnam. Stalin had blockaded Berlin's land approaches in 1948, a move broken by a massive American and British air-lift. He had decided to arm and train Kim Il Sung's North Korean army for the offensive war. The British Intelligence would have been seeking ways to make him more cautious.