Well, I sincerely doubt that the Taliban, who amount to .0005% of the population (more or less), could make the entire world "succumb" to anything. The last thing the Taliban need right now is even 5% of the world population on survival mode after their islamic ass. So I'd say they do not pose a threat to anyone. That doesn't mean they can't do anything stupid, like doing something with a nuke or giving someone a nuke to detonate it on their behalf here or in Uzbekhistan, but that would mean their total anihilation, so I'd say they will spread violence to a certain point, but they will not cross "the dotted line".
Debussey respectfully disagree with you here. Your post assumes that they are somewhat of a rational player, which = extremely doubtful. They won't be able to make the world "succumb" to anything, but it = very likely that they'd use nukes to cause as much damage as possible.
Just as an example: At this point a few thousand Taliban fuckers are trying to kick ass towards Islamabad. Their actual chances of success = very small, they encounter mass losses daily, but they are still willing to try (by destroying the lives of hundreds of thousands). This is not a sign of someone that won't cross "the dotted line". Neither is the normal "terrorist mind". A suicide bomber knows that if he blows himself up in a subway station, the actual damage will be very small, yet he does it (even though his end agenda = world domination of Islam, which makes suicide bombing a very ineffective strategy) due to his extremist beliefs, hate (which all these fuckers have plenty of) and to cause fear in the "opponent". There is little assurance to be found that the Taliban won't act on the same mindset if they get access to WMD, especially given the previous actions shown.
Even if the chance of Taliban going berzerk was 30%, the E(Damage) = 0,3*(damage from nukes) would justify annihilating them by any means necessary.
If anything, these morons can not be negotiated with. They must simply be destroyed by whatever means necessary.
