“China a short high intensity war into which they can feed their excess population, they have several dozen million men of military age that will never be able to get girlfriends let alone wives.”
Send them on a mission as cannon fodder to “denazify” some Russian land. Its ok, as Kazan, said, “borders change all the time” ;)
The Chinese are unlikely to try that given the outcome of the decades long Sino-Soviet border wars. They also don’t want to cut their own throats on oil and some military tech (which they both get from Russia).