Following Operation Barbarossa, many Jews in what was then Eastern Poland fell victim to Nazi death squads called "Einsatzgruppen", which massacred Jews, especially in 1941. Some of these German-inspired massacres were carried out with help from, or active participation of Poles themselves: for example, the Jedwabne pogrom, in which between 300 (Institute of National Remembrance's Final Findings) and 1,600 Jews (Jan T. Gross) were tortured and beaten to death by members of the local population. The full extent of Polish participation in the massacres of the Polish Jewish community remains a controversial subject, in part due to Jewish leaders' refusal to allow the remains of the Jewish victims to be exhumed and their cause of death to be properly established. The Polish Institute for National Remembrance identified twenty-two other towns that had pogroms similar to Jedwabne. The reasons for these massacres are still debated, but they included antisemitism, resentment over alleged cooperation with the Soviet invaders in the Polish-Soviet War and during the 1939 invasion of the Kresy regions, greed for the possessions of the Jews, and of course coercion by the Nazis to participate in such massacres.