Atomic spies

Last updated
Klaus Fuchs, arguably the most important of the identified "atomic spies" for his extensive access to high-level scientific data and his ability to make sense of it through his technical training. Klaus Fuchs ID badge.png
Klaus Fuchs, arguably the most important of the identified "atomic spies" for his extensive access to high-level scientific data and his ability to make sense of it through his technical training.

Atomic spies or atom spies were people in the United States, the United Kingdom, and Canada who are known to have illicitly given information about nuclear weapons production or design to the Soviet Union during World War II and the early Cold War. Exactly what was given, and whether everyone on the list gave it, are still matters of some scholarly dispute. In some cases, some of the arrested suspects or government witnesses had given strong testimonies or confessions which they recanted later or said were fabricated. Their work constitutes the most publicly well-known and well-documented case of nuclear espionage in the history of nuclear weapons. At the same time, numerous nuclear scientists wanted to share the information with the world scientific community, but this proposal was firmly quashed by the United States government.


Confirmation about espionage work came from the Venona project, which intercepted and decrypted Soviet intelligence reports sent during and after World War II. These provided clues to the identity of several spies at Los Alamos and elsewhere, some of whom have never been identified. Some of this information was available to the government during the 1950s trials, but it was not usable in court as it was highly classified. Additionally, historians have found that records from Soviet archives, which were briefly opened to researchers after the fall of the Soviet Union, included more information about some spies.


Before World War II, the theoretical possibility of nuclear fission resulted in intense discussion among leading physicists world-wide. Scientists from the Soviet Union were later recognized for their contributions to the understanding of a nuclear reality, and won several Nobel Prizes. Soviet scientists such as Igor Kurchatov, L. D. Landau, and Kirill Sinelnikov helped establish the idea of, and prove the existence of, a splittable atom. Dwarfed by the Manhattan Project conducted by the US during the war, the significance of the Soviet contributions has been rarely understood or credited outside the field of physics. According to several sources, it was understood on a theoretical level that the atom provided for extremely powerful and novel releases of energy, and could possibly be used in the future for military purposes. [1]

In recorded comments, physicists lamented their inability to achieve any kind of practical application from the discoveries. They thought that creation of an atomic weapon was unattainable. According to a United States Congressional joint committee, although the scientists could conceivably have been first to generate a man-made fission reaction, they lacked the ambition, funding, engineering capability, leadership, and ultimately, the capability to do so. The undertaking would be of an unimaginable scale, and the resources required to engineer for such use as a nuclear bomb, and nuclear power were deemed too great to pursue. [2]

At the urging of Albert Einstein and Leo Szilard in their letter of August 2, 1939, the United States  — in collaboration with Britain and Canada  — recognized the potential significance of an atomic bomb. They embarked in 1942 upon work to achieve a usable device. Estimates suggest that during the quest to create the atomic bomb, an investment of $2 billion, 86,000 tons of silver and 24,000 skilled workers drove the research and development phase of the project. [3] Those skilled workers included the people to maintain and operate the machinery necessary for research. The largest Western facility had five hundred scientists working on the project, as well as a team of fifty to derive the equations for the cascade of neutrons required to drive the reaction. The fledgling equivalent Soviet program was quite different: The program consisted of fifty scientists, and two mathematicians trying to work out the equations for the particle cascade. [4] The research and development of techniques to produce sufficiently enriched uranium and plutonium were beyond the scope and efforts of the Soviet group. The knowledge of techniques and strategies that the Allied programs employed, and which Soviet espionage obtained, may have played a role in the rapid development of the Soviet bomb after the war.

The research and development of methods suitable for doping and separating the highly reactive isotopes needed to create the payload for a nuclear warhead took years, and consumed a vast amount of resources. The United States and Great Britain dedicated their best scientists to this cause and constructed three plants, each with a different isotope-extraction method. [5] The Allied program decided to use gas-phase extraction to obtain the pure uranium necessary for an atomic detonation. [2] Using this method took large quantities of uranium ore and other rare materials, such as graphite, to successfully purify the U-235 isotope. The quantities required for the development were beyond the scope and purview of the Soviet program.

The Soviet Union did not have natural uranium-ore mines at the start of the nuclear arms race. A lack of materials made it very difficult for them to conduct novel research or to map out a clear pathway to achieving the fuel they needed. The Soviet scientists became frustrated with the difficulties of producing uranium fuel cheaply, and they found their industrial techniques for refinement lacking. The use of information stolen from the Manhattan Project eventually rectified the problem. [6] Without such information, the problems of the Soviet atomic team would have taken many years to correct, affecting the production of a Soviet atomic weapon significantly.

Some historians believe that the Soviet Union achieved its great leaps in its atomic program by the espionage information and technical data that Moscow succeeded in obtaining from the Manhattan Project. Once the Soviets had learned of the American plans to develop an atomic bomb during the 1940s, Moscow began recruiting agents to get information. [7] Moscow sought very specific information from its intelligence cells in America, and demanded updates on the progress of the Allied project. Moscow was also greatly concerned with the procedures being used for U-235 separation, what method of detonation was being used, and what industrial equipment was being used for these techniques. [8]

The Soviet Union needed spies who had security clearance high enough to have access to classified information at the Manhattan Project and who could understand and interpret what they were stealing. Moscow also needed reliable spies who believed in the communist cause and would provide accurate information. Theodore Hall was a spy who had worked on the development of the plutonium bomb the US dropped in Japan. [9] Hall provided the specifications of the bomb dropped on Nagasaki. This information allowed the Soviet scientists a first-hand look at the set up of a successful atomic weapon built by the Manhattan Project.

The most influential of the atomic spies was Klaus Fuchs. Fuchs, a German-born British physicist, went to the United States to work on the atomic project and became one of its lead scientists. Fuchs had become a member of the Communist Party in 1932 while still a student in Germany. At the onset of the Third Reich in 1933, Fuchs fled to Great Britain. He eventually became one of the lead nuclear physicists in the British program. In 1943 he moved to the United States to collaborate on the Manhattan Project. [10] Due to Fuchs's position in the atomic program, he had access to most, if not all, of the material Moscow desired. Fuchs was also able to interpret and understand the information he was stealing, which made him an invaluable resource. Fuchs provided the Soviets with detailed information on the gas-phase separation process. He also provided specifications for the payload, calculations and relationships for setting of the fission reaction, and schematics for labs producing weapons-grade isotopes. [11] This information helped the smaller under-manned and under-supplied Soviet group move toward the successful detonation of a nuclear weapon.

The Soviet nuclear program would have eventually been able to develop a nuclear weapon without the aid of espionage. It did not develop a basic understanding of the usefulness of an atomic weapon, the sheer resources required, and the talent until much later.[ when? ] Espionage helped the Soviet scientists identify which methods worked and prevented their wasting valuable resources on techniques which the development of the American bomb had proven ineffective. The speed at which the Soviet nuclear program achieved a working bomb, with so few resources, depended on the amount of information acquired through espionage. During the Cold War trials, the United States emphasized the significance of that espionage. [12]

Notable spies

Sketch of an implosion-type nuclear weapon design made by David Greenglass as state's evidence, illustrating what he gave the Rosenbergs to pass on to the Soviet Union. Greenglass bomb diagram.png
Sketch of an implosion-type nuclear weapon design made by David Greenglass as state's evidence, illustrating what he gave the Rosenbergs to pass on to the Soviet Union.

See also

Related Research Articles

Klaus Fuchs German-born British theoretical physicist and atomic spy (1911-1988)

Klaus Emil Julius Fuchs was a German theoretical physicist and atomic spy who supplied information from the American, British, and Canadian Manhattan Project to the Soviet Union during and shortly after World War II. While at the Los Alamos National Laboratory, Fuchs was responsible for many significant theoretical calculations relating to the first nuclear weapons and, later, early models of the hydrogen bomb. After his conviction in 1950, he served nine years in prison in the United Kingdom and then moved to East Germany where he resumed his career as a physicist and scientific leader.

Theodore Hall

Theodore Alvin Hall was an American physicist and an atomic spy for the Soviet Union, who, during his work on US efforts to develop the first and second atomic bombs during World War II, gave a detailed description of the "Fat Man" plutonium bomb, and of several processes for purifying plutonium, to Soviet intelligence. His brother, Edward N. Hall, was a rocket scientist who worked on intercontinental ballistic missiles for the United States government.

Cold War espionage

Cold War espionage describes the intelligence gathering activities during the Cold War between the Western allies and the Eastern Bloc. Because each side was preparing to fight the other, intelligence on the opposing side's intentions, military, and technology was of paramount importance. To gather information, the two relied on a wide variety of military and civilian agencies.

Julius and Ethel Rosenberg American couple executed for spying for the Soviet Union

Julius Rosenberg and Ethel Rosenberg were American citizens who were convicted of spying on behalf of the Soviet Union. The couple was accused of providing top-secret information about radar, sonar, jet propulsion engines, and valuable nuclear weapon designs; at that time the United States was the only country in the world with nuclear weapons. Convicted of espionage in 1951, they were executed by the federal government of the United States in 1953 in the Sing Sing correctional facility in Ossining, New York, becoming the first American civilians to be executed for such charges and the first to suffer that penalty during peacetime.

Soviet atomic bomb project Soviet program to develop nuclear weapons during World War II

The Soviet atomic bomb project was the classified research and development program that was authorized by Joseph Stalin in the Soviet Union to develop nuclear weapons during World War II.

Alan Nunn May

Alan Nunn May was a British physicist, and a confessed and convicted Soviet spy, who supplied secrets of British and United States atomic research to the Soviet Union during World War II.

David Greenglass Atomic spy for the Soviet Union

David Greenglass was an atomic spy for the Soviet Union who worked on the Manhattan Project. He was briefly stationed at the Clinton Engineer Works uranium enrichment facility at Oak Ridge, Tennessee, and then worked at the Los Alamos Laboratory in New Mexico from August 1944 until February 1946.

Michael Meeropol

Michael Meeropol is a retired professor of economics. He is the older son of Julius and Ethel Rosenberg, convicted communist spies. Born in New York City, as Michael Rosenberg, Meeropol spent his early childhood living in New York, and attending local school there.

Harry Gold

Harry Gold was an American laboratory chemist who is known for having been convicted as a courier for the Soviet Union to pass atomic secrets from Klaus Fuchs, an agent of the Soviet Union, during World War II. Gold served as a government witness and testified in the case of Julius and Ethel Rosenberg, who were convicted and executed in 1953 for their roles. Gold served 15 years in prison.

Ruth Greenglass

Ruth Leah Greenglass was an American citizen who acted as a spy for the Soviet Union along with her husband, David Greenglass.

Perseus (spy) Codename of a possible Soviet spy

Perseus was the code name of a hypothetical Soviet atomic spy that, if real, would have allegedly breached United States national security by infiltrating Los Alamos National Laboratory during the development of the Manhattan Project, and consequently, would have been instrumental for the Soviets in the development of nuclear weapons.

Joel Barr, also Iozef Veniaminovich Berg and Joseph Berg, was part of the Soviet Atomic Spy Ring.

Anatoli Yatskov

Anatoly Antonovich Yatskov, also known as Anatoli Yatzkov – was a Soviet consul in New York as well as intelligence officer handling American agents in the U.S. Manhattan Project during war. His spy cover was eventually blown by the U.S. Army Venona Program which identified him as a key NKVD agent involved in 1940s Atomic Spy Ring.

Leonid Kvasnikov

Leonid Romanovich Kvasnikov was a Russian chemical engineer and a spy, serving first in NKVD and later served in KGB. Graduated with honors from the Moscow Institute of Chemical Machine-Building in 1934 and worked as an engineer in a chemical plant for several years in the Tula region. Kvasnikov continued postgraduate engineering studies and joined the KGB in 1938 as a specialist in scientific-technical intelligence. Beginning in 1939 he was the section head of scientific and technical intelligence. Kvasnikov served a few short-term assignments in Germany and Poland and rising swiftly to become deputy chief and then chief of the KGB scientific intelligence section.

Nuclear espionage

Nuclear espionage is the purposeful giving of state secrets regarding nuclear weapons to other states without authorization (espionage). There have been many cases of known nuclear espionage throughout the history of nuclear weapons and many cases of suspected or alleged espionage. Because nuclear weapons are generally considered one of the most important of state secrets, all nations with nuclear weapons have strict restrictions against the giving of information relating to nuclear weapon design, stockpiles, delivery systems, and deployment. States are also limited in their ability to make public the information regarding nuclear weapons by non-proliferation agreements.

Arnold Kramish was an American nuclear physicist and author who was associated with the Manhattan Project. While working on the project, he was nearly killed in an accident at the Philadelphia Naval Yard where a prototype thermal diffusion isotope separation device was being constructed. The priest of the Philadelphia Naval Yard offered last rites to Kramish, who refused, as he was Jewish. After World War II, he wrote numerous books on nuclear issues. He is perhaps best known for his book The Griffin - the greatest untold espionage story of World War II, about Paul Rosbaud, who passed important scientific and military information from Germany to the Allies.

<i>Nuclear Secrets</i>

Nuclear Secrets, aka Spies, Lies and the Superbomb, is a 2007 BBC Television docudrama series which looks at the race for nuclear supremacy from the Manhattan Project through to Pakistan's nuclear weapons programme.

Robert J. Lamphere FBI agent

Robert J. Lamphere was former an agent of the Federal Bureau of Investigation (FBI) involved in the cases of atomic spies Klaus Fuchs, Harry Gold, Julius Rosenberg, and Ethel Rosenberg, as well as British spy Kim Philby. "He had a hand in every major Soviet spy case from the end of World War II through the mid-1950s."


  1. Schwartz, Michael. The Russian-A(merican) Bomb: The Role of Espionage in the Soviet Atomic Bomb Project. J. Undergrad. Sci. 3: 103–108 (Summer 1996)
  2. 1 2 Joint Committee on Atomic Energy. Soviet Atomic Espionage. Chapters 2–3 United States Government Printing Office, Washington, 1951.
  3. Schwartz, Michael. Russian Bomb 103-08
  4. Schwartz, Michael. Russian Bomb 103-08f
  5. Allen Weinstein and Alexander Vassiliev, "Atomic Espionage: from Fuchs to the Rosenburgs" in The Haunted Wood, (New York: Random House Inc, 1999), 172–222.
  6. Weinstein and Vassiliev (1999), "Atomic Espionage," 180–85
  7. Weinstein and Vassiliev, "Atomic Espionage," pp. 190–200
  8. Weinstein and Vassiliev (1999), "Atomic Espionage," 180
  9. Holmes,Marian. "Spies Who Spilled Atomic Bomb Secrets". Smithsonian Magazine, 20 April 2009.
  10. Holmes, Spies Who Spilled, 1–2
  11. Weinstein and Vassiliev, "Atomic Espionage", 200–210
  12. Joint Committee Chapter 2
  13. "Morris Cohen, 84, Soviet Spy Who Passed Atom Plans in 40's". The New York Times. 5 July 1995. Retrieved 2008-07-07. Morris Cohen, an American who spied for the Soviet Union and was instrumental in relaying atomic bomb secrets to the Kremlin in the 1940s, has died, Russian newspapers reported today. Mr. Cohen, best known in the West as Peter Kroger, died of heart failure in a Moscow hospital on June 23 at age 84, according to news reports.
  14. A.M. Hornblum, The Invisible Harry Gold (Yale University Press, 2010) kindle edition. locations 4030-37
  15. Pace, Eric (January 29, 1988). "Klaus Fuchs, Physicist Who Gave Atom Secrets to Soviet, Dies at 76". The New York Times. Retrieved 2008-07-07. Klaus Fuchs, the German-born physicist who was imprisoned in the 1950s in Britain after being convicted of passing nuclear secrets to the Soviet Union, died yesterday, the East German press agency A.D.N. reported. He was 76 years old.
  16. "Klaus Fuchs". TruTV . Retrieved 2008-07-07. His name was Klaus Emil Fuchs, and he was, as it has been shown by history, the most important atom spy in history. Not any of the notorious names in the saga of the theft of the atom bomb secrets Alan Nunn May, Julius and Ethel Rosenberg, and David Greenglass had been as important to the Russian effort as Klaus Fuchs.
  17. "Trinity by Frank Close review – in pursuit of 'the spy of the century'". The Guardian. 17 August 2019. Retrieved 2 January 2021.
  18. "1972 Death of Harry Gold Revealed". The New York Times. February 14, 1974. Retrieved 2008-07-07. Harry Gold, who served 15 years in Federal prison as a confessed atomic spy courier, for Klaus Fuchs, a Soviet agent, and who was a key Government witness in the Julius and Ethel Rosenberg espionage case in 1951, died 18 months ago in Philadelphia.
  19. "Greenglass, in Prison, Vows to Kin He Told Truth About Rosenbergs". The New York Times. March 19, 1953. Retrieved 2008-07-07. David Greenglass, serving fifteen years as a confessed atom spy, denied to members of his family recently that he had been coached by the Federal Bureau of Investigation in the drawing of segments of the atom bomb, or that he had given perjured testimony against his sister, Mrs. Ethel Rosenberg, and her husband, Julius.
  20. 1 2 Cowell, Alan (November 10, 1999). "Theodore Hall, Prodigy and Atomic Spy, Dies at 74". The New York Times. Retrieved 2008-06-26. Theodore Alvin Hall, who was the youngest physicist to work on the atomic bomb project at Los Alamos during World War II and was later identified as a Soviet spy, died on Nov. 1 in Cambridge, England, where he had become a leading, if diffident, pioneer in biological research. He was 74. ... Mr. Albright and Ms. Kunstel say Mr. Hall and a former Harvard roommate, Saville Sax, approached a Soviet trade company in New York in late 1944 and began supplying critical information about the atomic project.
  21. William J. Broad (Nov. 12, 2007), "A Spy's Path: Iowa to A-Bomb to Kremlin Honor", The New York Times p. A1
  22. John Earl Haynes; Harvey Klehr; Alexander Vassiliev (2010). Spies: The Rise and Fall of the KGB in America. Yale University Press. ISBN   978-0-300-15572-3.
  23. Michael Walsh (May 2009), "George Koval: Atomic Spy Unmasked", Smithsonian
  24. John Earl Haynes; Harvey Klehr (2000). Venona: Decoding Soviet Espionage in America. Yale University Press. ISBN   0300084625 via Google Books.
  25. "Alan Nunn May, 91, Pioneer In Atomic Spying for Soviets". The New York Times. 25 January 2003. Retrieved 2008-07-07. Alan Nunn May, a British atomic scientist who spied for the Soviet Union, died on Jan. 12 in Cambridge. He was 91. ... One of the first Soviet spies uncovered during the cold war, Dr. Nunn May worked on the Manhattan Project and was betrayed by a Soviet defector in Canada. His arrest in 1946 led the United States to restrict the sharing of atomic secrets with Britain.
  26. "Execution of the Rosenbergs". The Guardian. London. June 20, 1953. Retrieved 2008-06-24. Julius and Ethel Rosenberg were executed early this morning at Sing Sing Prison for conspiring to pass atomic secrets to Russia in World War II.
  27. "The Rosenbergs: A Case of Love, Espionage, Deceit and Betray". TruTV . Retrieved 2008-07-07. Julius and Ethel Rosenberg were charged with the crime of conspiracy to commit espionage, and tried under the Espionage Act of 1917.
  28. "Execution of the Rosenbergs". The Guardian . London. June 20, 1953. Retrieved 2008-06-24. Julius and Ethel Rosenberg were executed early this morning at Sing Sing Prison for conspiring to pass atomic secrets to Russia in World War II.
  29. Broad, William J. (2019-11-23). "Fourth Spy Unearthed in U.S. Atomic Bomb Project". The New York Times. ISSN   0362-4331 . Retrieved 2019-11-28.
  30. "Morton Sobell Free As Spy Term Ends". The New York Times . January 15, 1969. Retrieved 2008-07-07. Morton Sobell, sentenced to 30 years for a wartime espionage conspiracy to deliver vital national secrets to the Soviet Union, was released from prison yesterday after serving 17 years and 9 months.
  31. Roberts, Sam (September 11, 2008). "For First Time, Figure in Rosenberg Case Admits Spying for Soviets". The New York Times . In an interview on Thursday, Mr. Sobell, who served nearly 19 years in Alcatraz and other federal prisons, admitted for the first time that he had been a Soviet spy.
  32. "Адамс Артур Александрович". Retrieved 2020-04-16.

Further reading