Complex sentence: The main assignment of BKA were anti-partizan operations in which some 30,000 Jews were killed in total (usually during pacification of villages), and later at the front against the Red Army.
Split into simpler sentences: The main assignment of BKA were anti-partizan operations in which some 30,000 Jews were killed in total (usually during pacification of villages). Later, BKA was used at the front against the Red Army.