I think the 20 nukes is just frustration speaking. And of course no stealth fighter could carry 20 nukes anyway. A B2 might carry 8, depending. Each would have an explosive yield about 10x that of Nagasaki, and with targeting could kill a million people on detonation, given city densities now, and perhaps that many more later.
So, you kill off 40 million Chinese, none of whom had anything to do with this, and their population drops from 1.393 billion to, get this, 1.353 billion.
And they would counter attack of course. And we would counter that. etc.