The Einsatzgruppe commanders, with the exception of Einsatzgruppe A's Stahlecker, were of the opinion by the fall of 1941 that it was impossible to kill the entire Jewish population of the Soviet Union in one sweep, and thought the killings should stop.[107] An Einsatzgruppe report dated 17 September advised that the Germans would be better off using any skilled Jews as labourers rather than shooting them.[107] Also, in some areas poor weather and a lack of transportation led to a slowdown in deportations of Jews from points further west.[108] Thus, an interval passed between the first round of Einsatzgruppen massacres in summer and fall, and what American historian Raul Hilberg called the second sweep, which started in December 1941 and lasted into the summer of 1942.[109] During the interval, the surviving Jews were forced into ghettos.[110]