Sorry OP, but there are some problems with your scenario.

1) Ever hear of mutual assured destruction? If they attacked, all it would take is one nuclear sub, ONE, to end Russia and china as week know it. 24 missles x 3 warheads per missle = 72 targets. So the top 30 targets in each country would be destroyed, with a few targets hit multiple times and a couple of upper atmosphere EMP shots. That would end both those countries as we know it. And it is the reason why there has not been a full scale nuclear war. Both sides would be utterly destroyed.

2) If they felt the need to attack us, they would probably do so indirectly by supplying "terrorists" with pakistan nukes and going that route. An EMP attack by "terrorists" is also a possibility. But both of these are remote because if they are caught or even suspected, we are back to step one.

3) What is likely, however, is that they would pull the rug out from us financially. Sell all US bonds, quit selling gas/oil/resouces to the US/allies, and remove the dollar as the reserve currency.

4) Why attack the US and the west when it is collapsing all on it's own? The Chinese in particular are very patient. All they have to do is make sure their house is in order, wait for the US to collapse, and suddenly they are the superpower