In practice abandoning its 'official socialist' ideology of the "fraternity of peoples", the Soviets in the Great Terror of 1937–1938 targeted "a national group as an enemy of the state." During their "Polish operation" against party enemies the NKVD hit "Soviet Poles and other Soviet citizens associated with Poland, Polish culture, or Roman Catholicism. The Polish ethnic character of the operation quickly prevailed in practice... ." Stalin was pleased at "cleaning out this Polish filth." Among the several different nationalities targeted in the Great Terror (e.g., Latvians, Estonians, Finns, Belarusians), "ethnic Poles suffered more than any other group." In 1940 the Soviets also killed thousands of Polish POWs, among about 22,000 Polish citizens shot in the Katyn forest and other places.