Complex sentence: The military of the Soviet Union frequently committed war crimes at the direction of its government which included waging wars of aggression, mass murder of prisoners of war and repressing the population of conquered countries.
Split into simpler sentences: The military of the Soviet Union, also, frequently committed war crimes, which are today known to have been at the direction of its government. These crimes included waging wars of aggression, mass murder of prisoners of war and repressing the population of conquered countries.