Discussion continued in a more appropriate thread.
"The training materials show Russia's eastern military district was rehearsing multiple scenarios including using nukes against China in a Chinese invasion."
Its possible Russians suspect Reunification of Outer Manchuria (Historical Chinese regions invaded by Russia) with Mainland during the taiwan contingency
I'm late to this short party, but only for a tiny while.
While this "leak" may be yet another ploy to fray Beijing-Moscow relations in the backdrop of the Russo-Ukraine war - Nobody should be surprised if the leaks (or anything which happens to be similar/resembling in the future) have any credibility or accuracy.
We can be idealists at times, but we must be realists at all times.
Remember that Beijing and Moscow were at each others' throats for months in 1969, and Moscow even contemplated nuking China if the skirmishes at Dongbei erupted into an all-out war between the two red giants. It wasn't until the beginning of the 1990s when both sides started to warm their bilateral relations.
And we haven't even gone into the multiple conflagrations that both Tsarist Russia and USSR had with Qing China and the ROC in the past 100+ years.
While China and Russia are back-to-back with one another today, it would be wrong to assume that this situation is set in stone until the end of time, especially considering how both Russia and China got their massive territories over the past hundred of years.
If anything, we should understand that Beijing certainly will have/already have wargamed and planned for any possibility of conflict or war with Russia (in terms of conventional war and also nuclear strikes against Russia), just as how Moscow would've done the same WRT any possibility of conflict or war with China. We just don't see them surfacing in the public discourse, mostly due to the present geopolitical and political-economic-societal developments and realities between both countries.
One golden rule -
There are neither eternal friends nor eternal enemies, only eternal interests.