The Jawa Report makes the case for nuking Mecca proactively:
Today we are told by Muslims that the true meaning of jihad is internal struggle. Unfortunately, the actions of too many Muslims shows that they believe jihad means armed struggle against the infidels. Destroying Mecca may have the long-term affect of convincing radical Muslims that Allah really doesn't want sharia law around the world. That all that stuff about killing the infidels in the Quran--that's all metaphor.
Silent Running describes what he wants in order to avoid having a US city nuked:
4) I want a President who will outline what sort of victory we require, and what we will need to do to achieve it. And then I want him to do whatever is needed to achive it, and if anyone feels like sabotaging it in any way because it offends their delicate post-modernist sensibilities I want him to personally sign their execution warrants. Think I'm extreme? Take a look at how Abraham Lincoln tossed the constitution into the shredder for the duration of the Civil War and then tell me I'm extreme. He suspended free speech and had people who encouraged young men not to enlist shot, and he was right to do it.
This is not a game. We are not playing. The survival of human civilisation is at stake here. This isn't a war like all the others though. It will be fought militarily, economically, politically, culturally, ideologically and most important of all, religiously. A front in this war can be a jungle encampment in the southern Philippines, an airliner in the skies of Europe, a skyscraper in Sydney, a crowded market in Yemen, a synagogue in Haifa, a TV channel in Dubai, an internet chatroom in cyberspace...almost any setting in fact. The combatants are you and me.
From my standpoint, I don't think an American city being nuked would destroy human civilization. It would be bad. It would probably lead to retalitory strikes, the US economy being put on a war footing like we had for WWII, and police action the likes of which people who think their speech is being suppressed now can't imagine, but not the end of human civilization.
On the other hand, I think it would be possible for biologic agents and maybe chemical agents to lead to the end of human civilization. And I think the terrorists are fanatical enough to use them. And I think when it comes down to him or me, I choose me.
Hmm. Makes me want to write scifi describing a world in which the jihadiis win.
Enough. Time to kick demon butt.
Update: also see, of course, Deterence.