Klaus Fuchs and the Soviet Mapping of the American State
By Vera Kessler ·
For decades, the U.S. government held a mirror to its own infiltration, keeping the decryption of Soviet telegrams secret while agents stole the atomic bomb.
The theft of the atomic bomb was not a sudden heist but a long-term lease of the American state by the Soviet Union. The cost was the permanent loss of a nuclear monopoly and the compromise of the most sensitive corridors of power in Washington and London. This analysis is drawn from the archival scope-and-content descriptions of the records rather than the original telegrams themselves.
The Atomic Theft
The breach began in the laboratories and ended in the telegrams. The record establishes that Soviet agents, including Klaus Fuchs, a German theoretical physicist who supplied the Soviets with Manhattan Project calculations before serving nine years in a British prison, successfully funneled the secrets of the U.S. atomic bomb project to Moscow. Fuchs did not act alone; the record lists a cell of collaborators—Harry Gold, David Greenglass, Theodore Hall, and Julius and Ethel Rosenberg—all of whom provided the Soviets with the technical blueprints of the first nuclear weapons.
This was a precision operation run by the Soviet foreign intelligence services, specifically the First Main Directorate of the Committee for State Security, the organization responsible for managing covert agents and acquiring political and technical intelligence for the Soviet Union. To maintain this pipeline, the Soviets relied on a sprawling network of agencies. The public record identifies the NKVD, the People's Commissariat for Internal Affairs, as the secret police that held a monopoly on state security and carried out the Great Purge, and the NKGB, the Soviet intelligence and counter-intelligence force that operated in two stints between 1941 and 1946. These agencies did not just want the bomb; they wanted the machinery of the state that produced it.
The Unrecoverable Passages
The United States was not blind, but it was slow. The record shows that the U.S. began intercepting and decrypting Soviet diplomatic telegrams in 1943 under the U.S. Army, a program later absorbed by the National Security Agency, the intelligence agency of the Defense Department responsible for global monitoring and processing of signals intelligence. The program was given the random codename VENONA.
The record reveals a technical struggle between the cryptanalysts and the Soviet cipher clerks. The decrypted messages are marked with two distinct failures of intelligence. "Unrecovered" indicated that the cryptographers simply lacked enough text to produce a translation. "Unrecoverable" indicated passages that could not be decrypted because the Soviets did not inadvertently reuse portions of earlier ciphers. The public record establishes that the reuse of ciphers was the critical error that gave the U.S. the "break" needed to read the traffic.
There is a sharp irony in these gaps. The "unrecoverable" passages are not merely technical failures; they are the fingerprints of Soviet counter-intelligence. When a passage becomes unrecoverable, it suggests the moment the Soviet apparatus realized its security was compromised and shifted its cryptographic protocols. The gap is the shape of a realization.
The DOJ and the War Department
The scope of the infiltration extended far beyond the physicists at Los Alamos. The record documents a systemic penetration of the U.S. government, citing agents who had infiltrated the Department of Justice, the Department of State, the Department of the Treasury, the Office of Strategic Services, and the War Department. The reach extended into the White House, Congress, and the defense industries.
This was a mirrored operation in Great Britain, where Soviet intelligence utilized the island as a primary hub for its agents. The record names the "Cambridge Five"—specifically Guy Burgess, Donald Maclean, and Kim Philby—as British Intelligence double agents who fed the Soviets high-level secrets.
While the nuclear theft dominated the headlines, the record shows the Soviet foreign intelligence services were managing a diverse portfolio of misery and desperation. The files include attempts to free Ramon Mercader, the agent who murdered Leon Trotsky in Mexico, and the hunt for Viktor Kravchenko, a Soviet defector. They even tracked Soviet sailors who deserted from merchant ships in U.S. ports. These were the housekeeping tasks of an empire that had successfully turned the West's own bureaucracies into its collection points. The GRU, the foreign military intelligence agency of the Soviet Armed Forces, provided the military layer to this espionage, ensuring that the intelligence gathered by political agents was weaponized for the General Staff.
A Passive Harvest
The timeline of the Venona project is the most damning evidence in the file. The record explicitly states that although most of the messages were created and intercepted during World War II, most were not translated until after the war. The U.S. had the data, but it lacked the translation, and once it had the translation, it often lacked the will to act with immediacy.
The desk's reading is that the U.S. intelligence community prioritized the mapping of the Soviet network over the immediate neutralization of agents. By allowing the infiltration to persist, the U.S. effectively treated the breach as a passive intelligence collection operation. They preferred to watch the Soviet priorities unfold in real-time rather than risk the diplomatic fallout or the loss of a window into Moscow's operational logic. The infiltration was not a failure of security, but a calculated decision to trade security for visibility.
This pattern suggests that the redacted sections of the parallel series—the "Public Release Copies of Records Relating to Project Venona, 1942-1967"—are not protecting the identities of long-dead spies. The desk's reading is that those redactions hide the specific technical breaks and SIGINT methodologies that remained viable well into the late twentieth century. The government is not hiding who the traitors were; it is hiding how it still listens. The gaps in the archive protect the method, not the man, ensuring that the same machinery used to catch Fuchs continues to operate in the shadows of the present.