Point accepted Pongo, and it no doubt happens, and I don't want any nukes going off anywhere.
However, it still seems a rather tougher ethical question for me, because life usually isn't as easy and clear cut as your scenario - it would actually be more likely that they don't know for certain there's a nuclear bomb at all, they don't know for certain the 3 guys know where it is (if it exists), or even they don't know for certain the 3 guys have done anything wrong.
And even if they do - how do we know they know this? How do we know that suspect #3 really is a terrorist at all and not just someone Agent #2 found in bed with his wife? Or a journalist who was about to expose the CIA for selling drugs to buy arms for some South American guerilla army?
The whole human rights thing is unfortunately a whole heap trickier than your scenario suggests, and made even more tricky by the secrecy needed to provide good counter-terrorist intel - because if you torture the wrong guy, what recourse does he have? Who is accountable? It is far easier for the CIA to deny all knowledge and dismiss the guy as a nutter or just kill him (he had a heart condition - we didn't know) -any files will not be released for decades, if ever [classified for reasons of National Security].
Which brings us to Gunthr's comment
There is no problem with torturing terrorist suspects for information, ethically or legally, as long as the information isn't for use in a US court of law.
Gunthr - I have to ask this: who would you exempt from being suspected of terrorism? How, and who decides who is a terrorist or a suspected terrorist and who isn't?
As far as I see it, any law enforcemnet agency trying to stop terrorism has to be able to consider any- and everybody as a terrorist suspect in order to be effective, and so you might as well say:
"There is no problem with torturing US citizens or foreign nationals for information, ethically or legally, as long as the information isn't for use in a US court of law."
Sounds like a very scary country to live in to me.

Indeed a good test for how totalitarian these sorts of statements sound is to replace the word "terrorist" with the words "enemies of the Communist party" and "US" with "China", and then see if you can still back it as justifiable.
"There is no problem with torturing enemies of the Communist party for information, ethically or legally, as long as the information isn't for use in a Chinese court of law."
Still sound OK? Sounds like a front page shock-horror story to me: "Evil commies violate human rights again"
