Depends how it's used but if you fear by terrorists, it would probably cause relatively little damage to buildings apart from shattering windows and fittings, unless in scientifically-placed demolition charges that are not the usual terrorist method.
However, it would be enough to create a terrible anti-personnel weapon.
It could not bring down a Twin Tower then? I can't imagine the theft being of noble origin or goal or purpose. Maybe someone wants to blast a big hole in a mountain? What would it be used for originally? Thank you for your reply Durdle! :)
Durdle 