This will be a stranium on my cranium, but what the hey!
IIRC, thorium is not fissile - it can't be used for a bomb. As per the article, the thorium, in a reactor, will absorb neutrons to become U-233 but I don't believe U-233 is bomb material either. The U-233 would have to be somehow converted to U-238(?) to be suitable bomb material.
If I've botched that much then maybe someone will correct me.
That would be U-235 that is useful for bombs and it can not be done. U-233 will fission upon absorbing another neutron.