To smuggle the stuff out after the US got there, they
would have had to have 30 or 40 big trucks and get them
through checkpoints which were set up on the roads.
Anyone trying to come through checkpoints with a load of
explosives would have been shot as a suicide bomber, or at
the least arrested and stuff seized.
1st, you are assuming that such security existed in the days and weeks after April 2. 2nd, for them to take it out between March 8 and April 2 would have required the same type of convoy, and at the time we were actively monitoring this site with aircraft and satellite surveillance, as it was a suspected WMD site. Doubt they would've been running 18 wheelers out of their without us knowing about it.