At the time of the Wannsee Conference, the killing of Jews in the Soviet Union had already been underway for some months. Right from the start of Operation Barbarossa—the invasion of the Soviet Union—"Einsatzgruppen" were assigned to follow the army into the conquered areas and round up and kill Jews. In a letter dated 2 July 1941, Heydrich communicated to his SS and Police Leaders that the "Einsatzgruppen" were to execute Comintern officials, ranking members of the Communist Party, extremist and radical Communist Party members, people's commissars, and Jews in party and government posts. Open-ended instructions were given to execute "other radical elements (saboteurs, propagandists, snipers, assassins, agitators, etc.)". He instructed that any pogroms spontaneously initiated by the occupants of the conquered territories were to be quietly encouraged. On 8 July, he announced that all Jews were to be regarded as partisans, and gave the order for all male Jews between the ages of 15 and 45 to be shot. By August the net had been widened to include women, children, and the elderly—the entire Jewish population. By the time planning was underway for the Wannsee Conference, hundreds of thousands of Polish, Serbian, and Russian Jews had already been killed. The initial plan was to implement "Generalplan Ost" after the conquest of the Soviet Union. European Jews would be deported to occupied parts of Russia, where they would be worked to death in road-building projects.