The American Couple Who Became KGB Spies — Morris & Lona Cohen | Cold War Files

Morris and Lona Cohen were the most successful American spies ever recruited by the KGB — a deep-cover illegal couple who stole nuclear and naval secrets for three decades across the United States and Britain. This documentary explains exactly how two Americans became central to one of the Cold War’s most damaging espionage networks.

From atomic courier routes inside the Manhattan Project to the Portland Spy Ring’s theft of NATO underwater detection research, this case shows how a single clandestine pipeline reshaped Soviet submarine development and altered naval power balance during the 1950s and 1960s.

In this episode, Cold War Files follows the Cohens’ complete operational path — recruitment by the NKVD, courier work for Theodore Hall, disappearance from FBI monitoring in 1950, retraining in Moscow, and their emergence in the United Kingdom as “Peter and Helen Kroger,” the communication hub supporting handler Gordon Lonsdale and source Harry Houghton.

Based strictly on declassified MI5 reports, FBI files, GCHQ intercept logs, naval technical assessments, and forensic evidence from the Ruislip raids, this documentary reconstructs the full mechanics of the KGB illegal residency: encrypted radio transmissions, microdot production, Minox photography, forged passports, and the theft of advanced sonar and torpedo research from the Admiralty Underwater Weapons Establishment.

The Portland Spy Ring investigation remains one of the most detailed counterintelligence cases ever recorded, illustrating how quiet insiders and deep-cover illegals can compromise thousands of pages of classified material before detection. Its impact reshaped NATO security procedures, British document-handling rules, and Cold War submarine warfare doctrine.

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