In 1969, https://en.wikipedia.org/wiki/Sino-Soviet_border_conflict#Battle_of_Zhenbao_(Damansky)_Island
What’s your point? Of course, they each war gamed the possibility of war between Russia and China. Why is that so hard to understand? After the collapse of the monolithic communist movement, they were in as much a Cold War between each other as we were with each of them. This is what Kissinger was up to when he reached out to the Chicoms, driving that wedge deeper. I’ll clue you in on another news blast, we’ve war gamed the possibility of war with each of them. The cozy relationship we’ve driven them into is not the norm.
Russia is in a much better position than us re: the Chinese. They’re numbers are growing here.
In 1969 China and Russia had a border war that almost went nuclear. It was shortly after that that Kissinger went to China
if that freaks you out, you might want to peak at some of the war gaming involving American citizens.