When Germany invaded the Soviet Union Kuznetsov, at his own request, was sent to join Soviet partisan units in the Nazi-occupied Ukraine. In 1942, the same year he became a member of the Communist Party, he fought as a member of the guerrilla group "Victors", led by Dmitry Medvedev, in central and western Ukraine. Kuznetsov was in charge of several complex operations involving assassinations and kidnappings of high-ranking Nazi officials in the Rivne and Lviv regions, such as successful operations against the German-appointed chief judge of Ukraine, the vice-governor of Galicia, the adviser to the Reichskommissar of Ukraine, three German generals and others. Kuznetsov was also the first intelligence agent to uncover German plans to launch a massive tank attack in the Kursk region, and information about German V-2 rockets, as well as about Operation Long Jump, Hitler's plan to assassinate the heads of the USSR, USA and Great Britain during the Tehran Conference. Kuznetsov was operating in Rivne (the capital of Reichskommissariat Ukraine) using the fake German identity of "Oberleutnant Paul Siebert". It was Kuznetsov who obtained information about the location of Hitler's "Werwolf" headquarters, near the city of Vinnitsya.