I wouldn't say it's IMPOSSIBLE, but if it's going to happen, it's going to be an acquire-and-detonate deal. I don't believe they're hauling around thirty suitcase bombs. One discovery would be enough to justify an entire takeover of the Middle East, so I'm not betting they'd take that chance.
If they get one, they'll use it as quickly as possible. I don't believe they have one at this time, contrary to the reports.
I'm with you. I just don't believe they can hide and maintain a nuke for very long and expect it to work.
Personally I am more concerned that one could enter a port on a container ship or tanker and be detonated right there.