According to several sources, one of the results of this conference was the German "Ausserordentliche Befriedungsaktion" (see: German AB Action operation in Poland), elimination of Krakow intelligentsia Sonderaktion Krakau and the Soviet Katyn massacre In his 1991 book "Stalin: Breaker of Nations", British historian Robert Conquest stated: "Terminal horror suffered by so many millions of innocent Jewish, Slavic, and other European peoples as a result of this meeting of evil minds is an indelible stain on the history and integrity of Western civilization, with all of its humanitarian pretensions". Also, Professor George Watson of Cambridge University concluded in his "Rehearsal for the Holocaust?" commentary (June 1981) that the fate of the interned Polish officers may have been decided at this conference. This is however disputed by other historians, who point out that there is no documentary evidence confirming any cooperation on that issue, that the existing Soviet documentation actually makes such cooperation improbable and that it is reasonable to say that Germany did not know about the Katyn massacre until the mass graves were analysed by the Katyn Commission.