Bor-Komorowski's description is disputed by Russian historian Oleg Vishlyov, who claims, based on the original Soviet documents, that the conference was not between NKVD and Gestapo, but between Soviet and German commissions dealing with refugees in both occupied territories and that the topic of discussion was allegedly the 'refugee exchange'. According to that author the conference had nothing to do with repressions against Poles or with the Katyn massacre.[7] Meanwhile, some historians (including Wojciech Materski) point out that there is evidence of clandestine murder operations conducted by both Soviet and German forces in 1939–1940 across occupied Poland, however, there is no evidence of direct connection between the NKVD prisoner massacres and the German AB-Aktion in Poland leading to massacre of several thousand prominent Poles in the same time-frame.[11]