The military’s so-called Massive Ordnance Penetrator, a 30,000-pound bunker buster bomb, requires an “urgent” upgrade, according to Pentagon officials who are trying to ensure that 20 of the bombs are battle-ready — possibly for use against Iran, though officials have been tight-lipped on potential targets.

The Air Force developed the bomb in conjunction with Boeing to attack concrete bunkers and tunnel facilities, and the Pentagon has requested $81 million in reallocated funds from Congress to get it ready for use.