By the way, Russia and China adjusted borders couple years ago. By peacefull process of course and according to interests of each and other.
Really? Did Russia lose or gain land?

I think it is impossible to have "small scale clash for territory" with nuclear state. They just can increase forces until nuclears can be applied by the military doctrine. So, nobody is interested in it.
I really do think that at least some nuclear armed states would tolerate a small scale skirmish without going nuclear. Whether or not the current leaders of Russia would, is irrelevant in my view because I don't think if there is going to be any conflict that it will happen soon.

What if there is an "uprising" in Siberia and T-14s that were "captured" from local Russian forces were used against the government forces? Perhaps if the T-14s sold to China are downgraded, then the T-14s that are captured from local Russian forces will also be mysteriously downgraded?

Do you think Chechen rebels receive outside help? Chechen rebels want to separate from the Russian Federation right? So, if in the future they are successful, would the Russian government launch a nuclear weapon? Wouldn't the radiation harm nearby parts of Russia?

Doesn't the United States support Chechen rebels? Or at the very least the Russian government thinks that they are supported by the United States (not easy to give sources because I don't speak Russian, I am relying on what I have heard in the past). Why has Russia not launch nukes at the US if they think that the US is behind attempts to take territory away from them? Or am I wrong in thinking the Russian government thinks the US is supporting the rebels?