Yes !
in 1970 on a diplomatic party, the Sovjet diplomat Andrei Gromyko ask
US diplomat Henry Kissinger this:
"will the USA intervene, wen USSR attack China with nuclear wapons ?"
"Yes we will intervene with nuclear wapons !" answer Kissinger loud !
the Chines diplomat notice this and start the Ping Pong Diplomacy
http://en.wikipedia.org/wiki/Ping_Pong_Diplomacy
Source: " War and Peace in the Nuclear Age" by John Newhouse
so you got a good base for China and Soviet war without Nuclear Wapons.