Well they were sort of convinced to become apart of a convenient ally at the time. They never saw things eye to eye and as soon as the war ended they withdrew from each other. As the cold war began it brought both of the countries to the brink of a nuclear war. After many in-differences, the soviet union collapsed (Because of the aid of the truman doctine, and the collapse of the berlin wall playing a factor), they came to even terms, slightly for the better of each others nations. Hope I helped!