Who said civil war? No one. Admittedly, in a civil war situation, you would right - a nuclear strike would be pointless. But if it was outside China... well, since I highly doubt the modern army would be lined up in neat little rows - or, indeed, be anywhere in a 12-mile radius - a nuclear strike would make sense. OK, so admittedly every other nation in the world would get ****** off at China for doing this (particularly whichever sorry country got the bomb/bombs detonated in its territory), but in the short term, it would be a decent solution. And I believe we're only talking short term here anyway.
As for the Han having bombs: well, yes, they did, but they lacked the means to fire them over long distances. Plus they weren't powerful enough to do anything to a modern army, particularly since no modern army would be in any sort of closely packed formation, so due to the small blast radius, and bombs the Han had would only kill one or two soldiers. This is even assuming they could get in range to properly utilise the bombs.
Besides, it's irrelevent; even if you discount nuclear weapons, modern China's technology could still easily trump anything the Han had. Machine guns would cut their troops to ribbons if nothing else. To summarise, to stand even a ghost of a chance, the Han would have to do the following:
1) Surprise the modern Chinese. This is vital.
While they still have the element of surprise:
2) Kill any and all Chinese military leaders.
3) Find a way to sabotage all
their heavy military equipment.
4) Find a way to disperse the remaining Chinese armed forces.
5) Use superior numbers and tactics to crush each pocket of resistance one by one.
Now, on each of those stages, a hell of a lot of things could go wrong. And even if everything went perfectly, I imagine the Han army would still end up decimated.
[center]Signature credited to Nathan (or whatever he decides to call himself next)MSN address: yamiken (at) hotmail (dot) co (dot) uk
[size=6](You know the drill, remove the spaces, replace the at with @ and the dot