first off you had communism in eastern europe and old soviet client states in the way. the question you should be asking is why has it been expanding its way eastward once the soviet union fell and east germany fell? there was no more warsaw pact either. so why does nato still exist and move constantly towards the east?   competency. expensive. the us not wanting use better weapons in nato for fear of them not performing well especially with the china possibility of invading taiwan. the more evil explanation is because they want europeans destroyed just like the slavs getting ground up. remember its all jews in charge.
United States