The Soviet and Chinese relationship was an interesting one. Mao disagreed with Khrushchev's liberal (compared to Stalin) policies, and China and the USSR became enemies. Vietnam (and Mongolia) were close Soviet allies to protect themselves from Chinese domination.

China allowed Soviet military aid passage through the country, but once the threat of having an American client cf. South Korea was waning (early 70s) repaired relations with the US and invaded Vietnam (1978).