They call it the Massive Ordnance Penetrator for a reason—and not because it's ready to star in a Pentagon porn flick. The MOP is massive, and designed to penetrate straight into someone's (Iran's) secret bunkers. Now it's ready.
The GBU-57, the MOP's official designation, is a formidable piece of ordnance for the B-2 bomber: it's 20 feet long, 30,000 pounds, GPS-guided, and will drill straight through reinforced concrete before detonating 5,300 pounds of explosives. That should be enough to obliterate "hidden" underground nuclear facilities or weapon stockpiles—say, the kind our pals in Iran and Syria are skipping around in. The Air Force hopes stuffing an MOP down a bunker's gullet will be enough to destroy the whole complex—5,300 pounds is a lot of pounds—or, even better, deter foes from building these bunkers in the first place.
The Pentagon hasn't said where it'll possibly use the bomb, because that much is obvious, but just yesterday Air Force Secretary Michael Donley said "If it needed to go today, we would be ready to do that. We continue to do testing on the bomb to refine its capabilities, and that is ongoing. We also have the capability to go with existing configuration today." Hold on to your bunkers. [The Aviationist]