The same people we are bombing now and plan to bomb. Tactical nukes would maximize damage in that area. No one walks out. I don't think that Bush would let them get away with spreading bio/chem agents in this country. We will see how this all works out.
However, that might offend the enemy, so we will most likely refrain from any such endeavors. Remember, right now we're engaged in hand-wringing about having to deal with things before ramadan starts. Can't go offending the enemy, nope nope nope.
It's a little hard to shoot entire continents with .223 rounds. Should it turn out that America's very survival is mortally and immediately threatened by foreignors, then one possible defensive posture is to wipe out all life on all other continents, with very few exceptions made. It's not out of the question, and it is certainly technically doable with our own arsenals of nuclear devices, chemical weapons, and biological munitions.
Make no mistake, a biological attack on the U.S. would be a VERY serious development.
Seems to me that if we nuke, we nuke the source.
Sadam.