[nevergore]

The sad issue is even if they are somewhat off on the charge and the shape, they device would still go "atomic" although the yield would be less......depending on the size, quality and amount of fissionable material a Hiroshima size yield could be expected.

[COEXERJ145]

It's possible but they might also might end up with nothing but a radiological bomb which doesn't produce nuclear yield. The main obstacle is getting enough highly enriched uranium (60% or better U-235) which isn't easy to come by. Reactor fuel wouldn't be good enough.