How much would Americans mind if Russia dropped a few nukes on Chechnya, and maybe a couple on the Afghan/?
Russia has fixed blame for the Moscow subway bombings on Chechen rebels, and the local Al Queda claimed credit. What if Putin is tired of not being able to respond effectively to a diffuse guerrilla enemy, and decides on a disproportional response? With a threat of follow-up bombs.
Yes, bombing the countryside is not like bombing a city. But any terrorists who weren't killed wouldn't be very popular with the other surviving locals.
So this is something we wouldn't do, but would we silently cheer on Russia?
(After all, with the new treaty they have to reduce their nuclear arsenal anyway.....)
Yes, using a nuke would be very bad.