Toad, skip the partitions. Different time, different issues. Simply a question of political opportunism. Germany and Austria were just as guilty.
As for the war of 1920... it started bit earlier. Poland before partitions of 1772 ( first partition ) encompased better part of today's Bialorus, Ukraine and Lithuenia. After WWI we wanted it back and were going to take it, whether everyone liked it or not.
What was forgotten was the fact that before 1772 poland ruled those areas ( with exception of Lithuenia ) on the master/slave level and slaves weren't quite ready to come back to the old situation. ( i think there has been a uprising against poland in ukraine every 3 years from 1500 to 1772 )
Whether CCCP stepped in with excuse or simply used it as an excuse for its own purpose is a question of persepctive. Ukrainians didn't like CCCP any better then they did Poland. ( still don't )
One thing is for sure. Poland of 1920 sure as hell wasn't very innocent.