I'm of the oppinion that the U.S. nuclear stockpile represents the ultimate "or else". If someone has to have nukes, I would much rather that it be the U.S. than some other country. Sure, you could make a pretty good arguemnt that there are cultures out there older, wiser, and perhaps under certain measures better than that of the U.S., but I don't think they have the same group mindset as the U.S. as a whole to make them good custodains of the nuke genie. With the U.S., they will never again be an acceptable first strike weapon, but were someone to hit us or our allies first, there would be no question that we would respond. That's probably one of the only things that kept India and Pakistan from obliterating each other back in the 80's, or Israel from obliterating their neighbors (that and the whole soviet protectorate state mutually assured distruction issue).
I firmly belive that despite the recently uncovered nuke tech smuggling operations, the main reason no terrorist has a nuke yet (to our knowledge) is that the countries of the world know that if we traced the bomb back to them, we would retaliate. Had one of the 9-11 planes been carrying a nuke, I garuntee you Afghanistan would no longer exist. A nuclear bomb, despite the relitivly straightforward principles in building one, is a complex device that requires precise machineing to build. Even if you have the plans and the refined material for the simplest device (a Uranium core device where a polonium enriched uranium central core slightly smaller than critical mass has a slug of uranium 235 large enough to make up the difference fired in by a device similar to a shotgun Sabot shell) the machining and construction materials required to build said device are only available at a limited number of fairly high tech facilities, that you generally couldn't use long enough to build a bomb without getting officially noticed.
At the end of the day, Large scale WMD terrorism can only exist if a sponsor country wants it to, and with the U.S. nuke arsinal, no country really wants to. Sure, some isolated group could make a chemical bomb, or boil several trillion castor beans to make some ricin, but not on a large enough scale to get us all.
The U.S. is actually reducing the overall number of available weapons. Sure, the ones we dismantle are done so very carfully, with all the parts stored in easilly acessable parts bins, and the nuke cores stored in pre-machined forms that just happen to be the right shape to be placed back into a bomb housing should the need arise, but they are not immidiatly available. The new devices we have built in the last 20 years have been mostly replacements for older 1960's era bombs, making them smaller, lighter, and slightly less long term radioactivity (eco-friendly bombs yay!). Someone finally wised up and realised that the public as a whole would rather see a nuke go off than chemical weapons, so they have been getting rid of many of those (but not the research to build them again if necessary)
I do find the plans to research much smaller nukes somewaht disturbing to a certain degree. The end result of that research would result in a nuke about the size of a hand grenade. If nothing else, wayyy to easy to sneak past security and radiation detectors for my comfort.
I know I'm rambling, but anyways the point I was going for is that despite the worldwide perception of Americans as arrogent cowboys with itchy trigger fingers (probably accurate as far as it goes), If you had to choose who to give the nukes too, we're the ones you want to give them to.
Besides, didn't you see armageddon? you never know when we might need to nuke the killer asteroid.