I think it can be interesting example of falsification of history.

Let's start from Katyń (do not mix with Khatyń).
Russians tell something like "ok we did it, but you did same earlier. you killed 20.000 our prisoners of war during polish-soviet war 1920". This is really good falsification because:
1. ok 20.000 their prisoners died, but they weren't killed. There were some pandemias after world war I and russian soldiers suffered most of them (same like rest of people around).
2. comparison to died soviet prisoners is joke when compared with ... number of polish murdered pow's.
Officialy into camps died about 3.000 + 5.000 at Syberia but .... Russian took much less prisoners of war. They were murdering (generally with sabres and after tortures) most of soldiers taken. There were massive executions of prisoners into every place when some of Poles surrendered.

Nowadays they seems to forget about their crimes and try to cpmpare their anti-human regime to Poland.