qnli question: What name refers to the period of instability during the rift between Tito and the USSR? sentence: The event was significant not only for Yugoslavia and Tito, but also for the global development of socialism, since it was the first major split between Communist states, casting doubt on Comintern's claims for socialism to be a unified force that would eventually control the whole world, as Tito became the first (and the only successful) socialist leader to defy Stalin's leadership in the COMINFORM.