again, as you can see. Who interrupted PRC's unification?

NK and USSR did. USSR didn't want PRC to make relation with US so used this to force US and PRC's hand. US then treated PRC as communist ally and ignore Mao's subtle overtures to US. US then went back on its word and prevented Taiwan from being unified. A domino effect that started by USSR and NK, then US, then PRC. After that, Mao basically lost his idealism for Soviet Communism and turned to Chinese Communism.