I do not believe our air support would trigger a nuclear exchange in the least, but it might blunt and stop the absolute take over of a free, freindly, allied nation that came to our aid when we called for help.
If we do nothing in this early stage of Putin's plans, to help them and they get trodden under, then I believe the impact of that will be something that is much more likely to lead, over time, to a much more severe nuclear risk.
I had initially thought that we could escort those transports in there with armed fighter escorts and dare the Rusians to challenge us. Apparently the troops are already either all there, or mostly there and there was no incident.
But that's my own opinion.
Originally I thought that we shouldn’t get involved. However, now that Russia has invaded Georgia beyond simply occupying S. Ossetia I don’t believe that we can afford to sit still and let an ally be crushed. We should use the same sort of brinkmanship that we used in the Cold War. Perhaps sending a carrier group into the Black Sea and relocating a fighter wing into Georgia. By doing that we would show the Russians that we are serious without actually attacking them and provoking WWIII.