Klaus Fuchs: The man who stole the atom bomb 
by Norman Moss.
Grafton, 216 pp., £12.95, April 1987, 0 246 13158 6
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On 10 September 1949 Michael Perrin, one of the heads of the British Atomic Energy Programme, was woken up by an urgent telephone call asking him to come to the communications room at the US Embassy in London. There his opposite number in the Pentagon asked that an RAF plane be sent to the upper atmosphere to check radioactivity detected by the US Air Force that appeared to signal a Soviet atomic explosion. The public confirmation of this momentous event stunned us. We had believed that Stalin first heard about the American atomic bomb from President Truman at the Potsdam Conference in August 1945, and we could not understand how the Russians had been able to overcome the formidable scientific and technical hurdles involved in the construction of the bomb in no more time than that taken by the cream of European and American physicists who started in early 1941 and exploded the first bomb in July 1945.

A few weeks before that telephone call Michael Perrin had received another disturbing piece of news. A coded message sent to Moscow by the Soviet Mission in New York during the war and only just deciphered by the US Signal Corps indicated that one Klaus Fuchs, a German-born member of the British team, had given them information on the atomic bomb project. Fuchs was arrested in London in February 1950, convicted of treason and sentenced to 14 years’ imprisonment. What he told the Russians was never revealed and is still classified information here (lest the Russians get to know of it?), but the British told the Americans and Norman Moss found full details in their FBI files.

Klaus Fuchs was born in 1911, the son of a German pastor with left-wing sympathies who taught his children the Lutheran precept of acting according to their own consciences rather than obeying established authority. Fuchs became a student at the time when German universities had turned into battle-grounds between the extremes of right and left. At first he sided with the Social Democrats, but when their weak opposition to the Nazis disappointed him, he joined the Communist Party. For this he was once beaten up and thrown into a river by Nazi thugs. When Hitler came to power in March 1933 Fuchs feared for his life and went into hiding until the Communist Party dispatched him to an anti-Fascist meeting in Paris. From Paris he went to England, where he became a research student in Nevill Mott’s great school of theoretical physics at Bristol; after this he worked at Edinburgh with the German physicist Max Born, who was one of the founders of wave mechanics. In the spring of 1940 Fuchs was arrested, interned and later deported to Canada together with hundreds of other German and Austrian refugees, including myself. We were taken back to England and released in January 1941.

The atomic bomb project was set in motion in 1940 by two refugee physicists in Birmingham, the German-born Rudolf Peierls and the Austrian-born Otto Robert Frisch, when they found that the critical mass of the fissile uranium isotope 235 needed for an explosion was no more than a few kilograms. In the summer of 1941 Peierls engaged Fuchs to help him with theoretical work on the project. Nine years later Fuchs confessed: ‘When I learned the purpose of the work, I decided to inform Russia and established contact through another member of the Communist Party.’ He made this high-handed decision despite the fact that he had freely signed the Official Secrets Act – which pledged him not to disclose anything he learned in the course of his work to an unauthorised person – and had applied for naturalisation as a British subject. That he would have to ‘swear by Almighty God that on becoming a British subject I will be faithful and bear true allegiance to his Majesty King George VI, his heirs and successors according to law’ seemed not to be a problem.

Fuchs is a brilliant mathematician and physicist; he also has an accurate memory and a remarkable ability to explain difficult concepts lucidly. I had some experience of this when he taught me theoretical physics during our internment at Quebec in the summer of 1940. These talents and the information accessible to him enabled him to provide the Russians with extensive instructions for the manufacture of fissile material and the construction of atomic bombs.

On that first occasion, Fuchs told the Russians that the building of an atomic bomb was possible in principle and that Britain was taking the first steps; he also informed them of the critical mass of a uranium bomb and of his own theoretical work on the separation of the rare fissile isotope of uranium 235 from its more abundant non-fissile partner. Later at Los Alamos, Robert Oppenheimer, the scientific leader of the project, drew Fuchs into scientific discussions on all its aspects, so that Fuchs was better-informed than most of the other scientists, whose knowledge was restricted to their own special task. Here is an example, in Fuchs’s own words, of information handed in one session to a Soviet agent at a town near Los Alamos:

Classified data dealing with the whole problem of making an atom bomb from fissionable material as I then knew the problem.

Information as to the principle of the method of detonating an atom bomb.

The possibility of making a plutonium bomb.

The high spontaneous fission rate of plutonium.

(It is this which causes fission to occur more quickly than in U-235.)

Much of what was then known concerning implosion.

The fact that high explosives as a type of compression was considered but had not been entirely decided upon.

The size as to outer dimensions of the high explosive component.

The principle of the lens system which had not at that time been finally adopted.

The difficulties of multi-point detonation, as this was the specific problem on which I was then working.

The comparative critical mass of plutonium as compared with uranium 235.

The approximate amount of plutonium necessary for such a bomb.

Some information as to the type of core.

The current ideas as to the need for an initiator.

On another occasion he handed over 13 papers and a report of thirty-five to forty pages on the separation of the uranium isotopes by diffusion. How easy it all was! General Groves, the American commander of the project, was notorious among the scientists for his obsession with security, but Fuchs could load a pile of secret documents, including a scale drawing of the plutonium bomb, into his car and drive out of the Los Alamos compound to hand them to a Soviet agent in a deserted street of the nearest town. Several such meetings took place with Soviet agents in America, and others before and afterwards in England.

When Fuchs did not have copies of the relevant documents, he wrote down the mathematical equations and technical data from memory before meeting the agent. He did all this without ever arousing the suspicion of the young English theoretician with whom he shared an office for two years, nor that of any of his other colleagues. Back in England, he was appointed head of the theoretical division of the Atomic Energy Research Establishment at Harwell, in which capacity he told the Russians that Britain was building its own atomic bomb before even the Cabinet knew of it. As a British civil servant he became a stickler for security. At meetings of the Anglo-American Declassification Committee (also attended by Donald Maclean!), he invariably voted for keeping atomic information classified. As a final irony, Fuchs refused to reveal to the Scotland Yard detective who questioned him the technical details he had passed to the Russians, on the grounds that the detective was not security-cleared.

When Fuchs was convicted, Parliament and the public wondered how a member of the Communist Party could have been allowed to work on the atomic bomb, but Attlee, who was then prime minister, assured the House of Commons:

Not long after this man came into this country – that was in 1933 – it was said that he was a Communist. The source of that information was the Gestapo. At that time the Gestapo accused everybody of being a Communist. When the matter was looked into there was no support for this whatever. And from that time on there was no support. A proper watch was kept at intervals.

When I mentioned this to a veteran physicist friend of mine recently, he interjected: ‘But Fuchs and I were in the same Communist cell when we were students at Bristol.’ Max Born, Fuchs’s former chief at Edinburgh, wrote about Fuchs: ‘He never concealed that he was a convinced communist. During the Russo-Finnish war everyone’s sympathies in our department were with the Finns, while Fuchs was passionately pro-Russian.’ On the other hand, Peierls had no idea that Fuchs was a Communist.

When Fuchs finally confessed, he seems to have had no idea that he had committed a crime and believed that he could return to Harwell as though nothing had happened. Fuchs had closed his mind to the consequences of his actions, even though he later analysed his behaviour with remarkable insight:

In the course of this work I began naturally to form bonds of personal friendship and I had concerning them my inner thoughts. I used my Marxist philosophy to establish in my mind two separate compartments. One compartment in which I allowed myself to make friendships, to have personal relations, to help people and to be in all personal ways the kind of man I wanted to be and the kind of man which, in personal ways, I had been before with my friends in or near the Communist Party. I could be free and easy and happy with other people without fear of disclosing myself because I knew that the other compartment would step in if I approached the danger point. I could forget the other compartment and still rely on it. It appeared to me at the time that I had become a ‘free man’ because I had succeeded in the other compartment to establish myself completely independent of the surrounding forces of society. Looking back at it now the best way of expressing it seems to be to call it a controlled schizophrenia.

Fuchs’s resolve to decide the fate of the world seems to have been born of an arrogance that bordered on megalomania, as became apparent in prison where he said to Peierls that when he had ‘helped the Russians take over everything’, he would tell their leaders what was wrong with their system. He has not lived up to that promise, however, and recently told a Western colleague visiting him in East Germany that Sakharov was a traitor who deserved harsher punishment than mere exile from Moscow. When Fuchs and I were interned together in Canada I attended his brilliant lectures, but I had no human contact with that pale, narrow-faced, thin-lipped, austere-looking man: being more interested in the physics he taught me than in the physicist, I did not mind. People who knew him better thought him a very cold fish. All Fuchs’s former colleagues whom Moss has interviewed have stressed his reticence. Edward Teller, the Hungarian-born creator of the hydrogen bomb and éminence grise behind Reagan’s SDI, found Fuchs ‘taciturn to a pathological degree’. When Teller heard the news of his arrest, he is said to have remarked: ‘So that’s what it was!’ An acquaintance told Moss that she had never heard Fuchs laugh. He had no close friends, never talked about his German past and appeared to be sexless.

Moss attributes Fuchs’s reticence to his desire to conceal his Communist past, but Born’s autobiography shows that he made no secret of it, at least before he started his double life. I suspect that part of his reticence stemmed from his family background: his grandmother, his mother and one of his sisters all committed suicide in fits of depression; his brother was a consumptive in hospital in Switzerland; his second sister, who lived in the United States, was hospitalised for schizophrenia in the late Forties, which suggests that Fuchs knew her to be mentally unbalanced. Fuchs may have been abnormal in being able to lock his activities into two watertight compartments and to close his mind to the implications of his spying for the colleagues who trusted him and the country that had given him shelter: but no more abnormal than Anthony Blunt, who made friends with the King while spying for Russia.

It has been said that Fuchs handed atomic secrets to an ally and that he merely put into effect the policy of sharing atomic secrets with the Soviet Union that the great Danish physicist Niels Bohr in vain urged upon Roosevelt and Churchill, but there is a world of difference between Bohr’s ideal of preventing a nuclear arms race by a policy of mutual trust and Fuchs secretly giving Russia a good start in the race by handing over to her his colleagues’ scientific results.

Before Fuchs was unmasked, the British and the Americans had been discussing ways of continuing their wartime atomic collaboration in peacetime, but afterwards American lack of faith in British security destroyed all prospects of joint work. According to Dean Acheson, who was Secretary of State at the time: ‘The talks with the British and Canadians returned to square one, where there was a deep freeze from which they did not return in my time.’ Fuchs must have been pleased to have rendered this further gratuitous service to Russia.

That Fuchs put atomic weapons into Stalin’s hands sooner than he would otherwise have had them isn’t in doubt: how much sooner is anyone’s guess. Russian physicists were working on the possibility of making an atomic bomb before they received Fuchs’s first report: Moss cites David Holloway’s book The Soviet Union and the Arms Race for evidence that it was this report which caused Stalin to give the project the highest priority. The former head of the Institute of Nuclear Research in East Germany estimates that Fuchs saved the Russians two years; Russian physicists told Peierls that Fuchs saved them between one and two years. I am sceptical of such estimates. Scientific research is an imaginative activity, dependent on qualities of mind that are beyond our comprehension. There is no linear progression from the appearance of a problem to its solution. During the Second World War the Germans failed even to start a sustained chain reaction in a nuclear pile because they had incorrectly determined one of the vital parameters. It might equally well have taken the Russians many more years to solve the very difficult problems involved had Fuchs not given them the solutions. What difference that would have made politically is even harder to guess. Moss has evidence to show that Stalin would not have incited North Korea to attack the South if he had not felt secure in the possession of atomic weapons. Would an American monopoly of atomic weapons have deterred the Russians from invading Hungary in 1956? We shall never know.

In the late Forties Fuchs began to have doubts about Russian policy which he expressed in his confession: ‘It is impossible to give definite incidents because now the control mechanism acted against me, also keeping away from me facts which I could not look in the face, but they did penetrate and eventually I came to a point when I knew I disapproved of a great many actions of the Russian Government and of the Communist Party, but I still believed that they would build a new world and that one day I would take part in it and that on that day I would also have to stand up and say to them that there are things which they are doing wrong.’ He also began to understand the values that had enabled Britain to prevail against the Nazis: ‘Before I joined the project most of the English people with whom I had made personal contacts were left-wing, and affected, to some degree or other, by the same kind of philosophy. Since coming to Harwell I have met English people of all kinds, and I have come to see in many of them a deep-rooted firmness which enables them to lead a decent way of life. I do not know where this springs from and I don’t think they do, but it is there.’ On being released from Wakefield Prison in 1959, Fuchs went to join his father in East Germany, where he married and is now a much honoured citizen, no longer plagued by doubts about the Communist Party line or by nostalgia for the British way of life. The shutters in his mind seem to have come down once more and stayed down.

Moss went to great pains to study all the documents relating to Fuchs and interviewed everyone who had contact with him. His spy thriller is better than fiction, but is marred by a host of minor errors: the physicist Georg Placzek is referred to as Ernst Pletschek; our internment camp on the heights above Quebec is described as Sherbrooke, while the real Sherbrooke was another camp a hundred miles away to which we were taken later. Sir Nevill Mott is said to have been awarded the Nobel Prize in 1954 instead of 1977. Niels Bohr is called Neils and Bünemann Bunemann. The physicist A.P. French is described as an American, but is a former English colleague of mine at the Cavendish Laboratory, which is in Cambridge and not, as the author states, in Oxford. Queen’s University is at Kingston, Ontario, not Windsor. When the Swiss-born physicist Egon Bretscher worked on the hydrogen bomb with Edward Teller he did experiments on the reaction of deuterium with tritium, not ‘calculations’. Sir Rudolf Peierls points out to me that Frisch did not ‘hit on the idea of nuclear fission’, but verified experimentally the existence of fission fragments; also that the explosive lenses of the plutonium bomb were designed, not to make the force on different parts of the sphere different, but to make the detonation waves arrive at the same instant all over the plutonium sphere.

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Vol. 9 No. 14 · 23 July 1987

SIR: I appreciate the sympathetic review by M.F. Perutz of my book Klaus Fuchs: The man who stole the atom bomb, and his correction of what he indulgently calls some minor errors, but I would like to clarify one point. Professor Perutz says: ‘Moss attributes Fuchs’s reticence to his desire to conceal his Communist past, but Born’s autobiography shows that he made no secret of it.’ In his autobiography My Life, Max Born, who took on Fuchs as a young researcher, said Sir Nevill Mott told him he sent him away from Bristol University because ‘he spread Communist propaganda among the undergraduates.’ But there is a footnote containing a comment by Sir Nevill to the effect that Born must have misunderstood something he said, because he does not remember his doing any such thing. In fact, none of Fuchs’s close friends knew he had been an active Communist in Germany. Fuchs did once defend Russia’s attack on Finland in 1939 in an argument with Born, as Professor Perutz says in his review and as I said in my book.

Norman Moss
London W12

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