Klaus Fuchs - Wartime Work and Espionage

Wartime Work and Espionage

At the outbreak of war, German citizens in Britain were interned. Fuchs was put into camps on the Isle of Man and later in Quebec, Canada, from June to December 1940. However, Professor Max Born intervened on Fuchs' behalf. By early 1941, Fuchs had returned temporarily to Edinburgh. He was approached by Rudolf Peierls of the University of Birmingham to work on the "Tube Alloys" program – the British atomic bomb research project. Despite wartime restrictions, he was granted British citizenship in 1942 and signed an Official Secrets Act declaration form.

A London message from the GRU, the Red Army's foreign military intelligence directorate, dated 10 August 1941, refers to the GRU reestablishing contact with Fuchs. His initial Soviet contact was known as "Sonia". Her real name was Ruth Werner – a German communist and a Major in Soviet Military Intelligence.

As Fuchs later testified, after Nazi Germany invaded the Soviet Union in 1941 he concluded that the Soviets had a right to know what the United Kingdom (and later the United States) were working on in secret. Hence he began transmitting military intelligence to the USSR, though the historical record is unclear about exactly when he started. Fuchs's testimony confirms that he contacted a former friend in the Communist Party of Germany, who put him in touch with someone at the Soviet embassy in Britain. His code-name was Rest.

In late 1943, Fuchs transferred along with Peierls to Columbia University, in New York City, to work on the Manhattan Project. Although Fuchs was "an asset" of GRU in Britain, his "control" was transferred to the NKGB when he moved to New York. From August 1944 Fuchs worked in the Theoretical Physics Division at Los Alamos, New Mexico, under Hans Bethe. His chief area of expertise was the problem of imploding the fissionable core of the plutonium bomb. At one point, Fuchs did calculation work that Edward Teller had refused to do because of lack of interest. He was the author of techniques (such as the still-used Fuchs-Nordheim method) for calculating the energy of a fissile assembly which goes highly prompt critical. Later, he also filed a patent with John von Neumann, describing a method to initiate fusion in a thermonuclear weapon with an implosion trigger. Fuchs was one of the many Los Alamos scientists present at the Trinity test.

From late 1947 to May 1949, Fuchs gave Alexander Feklisov, his case officer, the principal theoretical outline for creating a hydrogen bomb and the initial drafts for its development as the work progressed in England and America. Meeting with Feklisov six times, he provided the results of the test at Eniwetok atoll of uranium and plutonium bombs and the key data on U.S. production of uranium-235. By revealing that America was producing one hundred kilograms of uranium-235 and twenty kilograms of plutonium per month, Fuchs made it easy for Soviet scientists to calculate the number of atomic bombs the United States possessed.

Thus, because of Klaus Fuchs, leaders of the Soviet Union knew the United States was not prepared for a nuclear war at the end of the 1940s, or even in the early 1950s. The information Fuchs gave Soviet intelligence in 1948 coincided with Donald Maclean's reports from Washington, D.C. It was obvious to Josef Stalin's strategists that the United States did not have enough nuclear weapons to deal simultaneously with the Berlin blockade and the Communists' victory in China.

Fuchs later testified that he passed detailed information on the project to the Soviet Union through a courier known as "Raymond" (later identified as Harry Gold) in 1945, and further information about the hydrogen bomb in 1946 and 1947. Fuchs attended a conference of the Combined Policy Committee (CPC) in 1947, a committee created to facilitate exchange of atomic secrets between the highest levels of government of the U.S., Great Britain and Canada; Donald Maclean, as British co-secretary of CPC, was also in attendance. In 1946 when Fuchs returned to England as the first Head of the Theoretical Physics Division at the Harwell Atomic Energy Research Establishment, he was confronted by intelligence officers as a result of the cracking of Soviet ciphers known as the VENONA project. Under interrogation by MI5 officer William Skardon at an informal meeting in December 1949, Fuchs initially denied being a spy and was not detained. Later, in January 1950, Fuchs arranged another interview with Skardon and voluntarily confessed that he was a spy. Fuchs told interrogators the KGB acquired an agent in Berkeley, California, who informed the Soviet Union about electromagnetic separation research of uranium-235 in 1942 or earlier. He was prosecuted by Sir Hartley Shawcross and was convicted on 1 March 1950. He was sentenced the next day to fourteen years in prison, the maximum possible for passing military secrets to a friendly nation. In the infancy of the Cold War, the Soviet Union was nonetheless still classed as an ally, "a friendly nation". A week after his verdict, on 7 March, the Soviet Union issued a terse statement denying that Fuchs served as a Soviet spy.

Fuchs' statements to British and American intelligence agencies were used to implicate Harry Gold, a key witness in the trials of David Greenglass and Julius and Ethel Rosenberg in the USA.