There are a lot of Trotskyites in my synagogue with the explanation 'Stalin was a special evil guy' which does not feel adequate. Nor does it explain later Soviet opposition to Zionism/Israel. See for instance the linked article. The extent of the explanation relies on the syllogism 'the USSR did a bad thing because it was failed socialism headed by the vile man Stalin'; no explanation is attempted:

A few days later, on May 17, the bureaucratized Soviet Union under Joseph Stalin also recognized the Zionist State after initially expressing support for the creation of a Jewish state. The following day, May 18, Czechoslovakia, which was already part of the Soviet Bloc, added its recognition and later sent weapons to the Zionists.