Re: I've never heard that!
Remember, all I know about nukes is what I read in the papers. I do know that tritium (an isotope of hydrogen gas, mildly radioactive alpha-emitter, also used in glowing watch dials) figures prominently in their function. A valve that adjusts the amount of tritium in the bomb can even be used to "dial-a-yield." Also, a "suitcase nuke" is more like the size of a footlocker and would be damned heavy. No one is going to sneak it onto an airplane.
There are many others who have pointed out the tritium half-life issue. Check this out.