In 1939 Lehmann transferred to the Reich Security Main Office (RSHA), division IV. His responsibility was to prevent the Soviets from spying on the German armaments industry. This position enabled Lehmann to provide valuable information to the Soviets about German armaments. On 19 June 1941, Lehmann reported to the NKVD the exact date on which the Germans planned to invade the Soviet Union. Operation Barbarossa was launched on 22 June 1941. His message was telegraphed to Beria and Stalin, who noted in green ink "disinformation" on Lehmann's intelligence report.