Nor should they. That is strictly a matter between the US and Russia.
China is not in the same nuclear league as the ‘big two’ nations – yet – and obviously does not want its efforts to make that a ‘big three’ curtailed by any earlier than desired agreement. I can see their point.
The US, on the other hand, desperately wants (and that is showing) to nail things down at the earliest possible time – seeing themselves (I’m not sure why, since they are the only aggressor in the pack) potentially being double teamed at some future point, and knowing that they have no hope of countering that.
Serve them right. They shouldn’t have acted as the school bully when they were on top of the game. Leaving them with no friends, dodgy lieutenants, and no affordable or realisable back-up plan.
I suppose they could start to humbly try to act friendly towards others for a change and see where that takes them, but what have they got to offer in return for friendship? Well, there’s all the stuff they have stolen which could be returned or paid for, for a start.