The "Luftwaffe" retained air superiority into November, and Soviet daytime aerial resistance was nonexistent. However, the combination of constant air support operations on the German side and the Soviet surrender of the daytime skies began to affect the strategic balance in the air. From 28 June to 20 September, "Luftflotte" 4 original strength of 1,600 aircraft, of which 1,155 were operational, fell to 950, of which only 550 were operational. The fleet's total strength decreased by 40 percent. Daily sorties decreased from 1,343 per day to 975 per day. Soviet offensives in the central and northern portions of the Eastern Front tied down Luftwaffe reserves and newly built aircraft, reducing "Luftflotte" 4 percentage of Eastern Front aircraft from 60 percent on 28 June to 38 percent by 20 September. The "Kampfwaffe" (bomber force) was the hardest hit, having only 232 out of an original force of 480 left. The "VVS" remained qualitatively inferior, but by the time of the Soviet counter-offensive, the "VVS" had reached numerical superiority.