Wikipedia
Anti-Katyn is a propaganda campaign intended to reduce the impact of the Katyn massacre of 1940 — when approximately 22,000 Polish citizens were murdered by the NKVD on the orders of Joseph Stalin — by referencing the deaths of thousands of Russian and Red Army soldiers at Polish internment camps from 1919–1924.
"Anti-Katyn" first emerged around 1990. After the Soviet government admitted that it had previously tried to cover up its responsibility for the massacre by claiming that it was perpetrated by the Nazi German army, previously neglected research into the fate of Soviet POWs in Poland in 1920s was revived to be used as a "tit-for-tat" argument in the discussions of Katyn.
Polish historian Andrzej Nowak summarized "Anti-Katyn" as an attempt by some Russian historians and publicists to "overshadow the memory of the crimes of the Soviet system against the Poles, creating imaginary analogies or even justification" because of the earlier deaths of the prisoners of war.