The invasion in the Barbarossa campaign of 1941 came earlier than expected to the Soviet leadership, resulting in the catastrophic loss of over 4 million Soviet soldiers killed or captured. Nevertheless, the USSR managed to halt the German advance at the outskirts of Moscow and Leningrad. With spies providing the certain knowledge that Japanese forces in the far east would not attack Siberia, the Soviets were able to transfer large numbers of experienced forces from the far east, and in the Winter of 1941/1942 they used them to counter-attack the German Army Group Centre in front of Moscow.