Check the history of the different communist movements. Maybe an entrypoint would be this: today there is the Fourth International. The USSR was born out of the

Check the history of the different communist movements. Maybe an entrypoint would be this: today there is the Fourth International. The USSR was born out of the Third International with Lenin, and the Fourth International opposed/opposes the USSR's practices and because of that the USSR hunted them down using their agents whom eventually killed Trotski.