China stopped help from 1968 when the Vietnam war getting brutally to make friend with enemy of Vietnam, your later new master USA Uncle Sam.
"We always say that the Sino-Pak friendship is higher than the mountains and deeper than the oceans. But we need to think it seriously that how could we do to keep this momentum,"
It's similiar slogan when China used Vietnam as black chess to counter USA, when it was usless China can drop it and backed Khmer rouge to attack Vietnam let us bleeding after reunitify 1975 and attacked Vietnam 1979. Dirty Traitor !
I think Pakistan known it soon, to be carefully with them.