There are many obvious reasons why a nuke wasn't used. Some are stated here already. Most importantly, we would look like fools (More than we already do) and the reason being for that is our government knew for a long time what was to come. They just decided not to do anything about it. The Muslims had (and still have) money on a string dangling it in front of these men and all logical thinking is out of the window. The U.S is a complete joke when it comes to this war. Truly, some are trying to bring peace and end all this but they have failed to realize that radical religious groups will never go away. You can never kill them all. Besides, the group who were held responsible were not punished. Bush Jr. was too busy taking the opportunity to take vengeance for daddy in Iraq. Not to mention the HIGH factor of oil. I say it because it's true. No conspiracy theories. All researches and evidences are there. If we were actually going to punish the ones who did the deed, they wouldn't have sent rookie troops fresh into the military to track down Osama Bin Laden having him escape them IN THE MOUNTAINS on a wheelchair. Instead, all of our high ranking officers and strong military personnel were busy bombing innocent people in Iraq. I could go on about this all day. The whole thing just makes me mad.