That I can't help you with by stating facts I know, so I will simply theorize.
Nope.
Just kidding, I'll go more into why I believe that.

'Course, I guess you guys didn't notice the pause before I typed "just kidding"...
First reason being getting 21,000 tons of high explosives, though tough for Joe Everybody, would be a cinch for a terrorist organization. If that were
capable of creating a fusion reaction, we would have seen by now a couple of nukes go off since 1945.
Also, from my understanding, you need a dense and radioactive substance in order to have a nuclear reaction, and high explosives aren't. I could be
wrong, though, I haven't really done much research into nuclear weapong physics. Now that I think about it, I'm going to have to research that after
I finish reading
Plan of Attack,
Rumsfeld's War, and
The Price of Loyalty...