Yes. Because you're committing an error in logic and tactics.
If I had these weapons, and was in their shoes, I would not use them. At least as the opening salvo.
What if they waited until US forces were on the ground?
What if they waited to use them in a counter attack, not necessarily against us, but some other nation in a design to further destabilize the situation. Say... India, for example.
There are other tactical considerations than merely opening up with your best shot...
Trivia question-- the U.S. produced four nuclear devices in 1945. One was tested in New Mexico. Two were dropped on Hiroshima and Nagasaki. What happend to the 4th?
If you put yourself in Osama's shoes, he really has no legitimate reason to nuke the USA. From a strategic point of view he is better off using the nuke(s) he has in Afghanistan.
Keep in mind his REAL objective isn't killing Americans for the sake of killing Americans. What he wants is a Muslim revolution that turns the clock back to the great Muslim expansion of the middle ages. He wants the west out of the Muslim World. He wants to rid the muslim world of the Kings and so forth that generally are friendly to the West. How does he accomplish this?
Well, he knows that the muslims are generally suspicious and paranoid about the USA and Israel. He knows that while they generally will not join together in a jihad because of local differences/interests, they share one thing above all, namely their religion. It has been said many times that this isn't to be a "war" of Islam v. Christianity, although that is EXACTLY WHAT HE NEEDS if he is to accomplish his goal.
How do nuclear weapons accomplish this? Before moving to that analyze the WTC attack. Why did he do something that big? Something that we could not ignore? The only logical Answer is to draw us out. But why draw us out if the military might of the US and the whole world will end up crushing him? Surely he realizes that in the end he can't beat us by simply picking off even thousands of civilians at a time? He needs to get ISLAM moving against the West. Islam won't move against the west unless it sees itself under attack. As it now stands, it is merely arguable that Islam is under attack.
So, he waits till we start dropping bombs. Then he pops a nuke in Kabul, or Kandahar and blames it on the USA.
The Western World sees that this is nonsense and would naturally rally round the USA. The Islamic world, on the other hand thinks that this is typical Western hatred of Muslims. All of a sudden there is a groundswell of Islamic resolve. 1 Billion Muslims say in unison "See they hate us so badly that they indiscriminately nuke innocent afghans. American lives are worth more than Muslim ones. Islamic revolution sparks in maybe one or two countries where American troops are. Ideally Saudi Arabia, but maybe Pakistan.
USA responds by rushing troops hither and thither trying to cope with something that is now out of control. Meantime more nukes go off this time blowing up americans. This one they take responsibility for saying that it is payback. The US is now in an impossible position. Global Armegeddon or retreat.
Just a scenario, but one that has been bugging me. Comments are welcome.