Morris and Leontine Cohen

Soviet Illegals Behind the Atom Spy Rings

Introduction

Morris “Moishe” Cohen and his wife Leontine (“Lona”) Cohen – better known by their aliases Peter and Helen Kroger – were an American couple who became two of the Cold War’s most effective Soviet illegals, spies operating under deep cover without diplomatic protection. Active on both sides of the Atlantic, they played key roles in Soviet espionage rings that infiltrated the U.S. Manhattan Project and later the British Admiralty. The Cohens helped funnel American atomic bomb secrets to Moscow in the 1940s and, a decade later, relayed British naval innovations to the USSR. Their clandestine careers spanned from the Spanish Civil War through the height of East–West tensions, and their eventual unmasking in the Rosenberg spy network and the Portland Spy Ring became a textbook case of tradecraft and counterintelligence. Despite their betrayal of the United States and Britain, the Cohens were celebrated as heroes in the Soviet Union – a stark contrast that endures in historical interpretations of their legacy.