February 16, 2012: Last year, after nearly a decade of development, the U.S. Air Force ordered eight MOP (massive ordnance penetrator) GBU-57A/B bunker buster bombs. These 13.6 ton weapons cost $3.5 million each. But late last year the air force suddenly requested $81.6 million to make urgent improvements in the MOP. Not many details of what the improvements needed were revealed. But given the amount of cash requested to improve the capabilities of a weapon that costs less than $4 million each, it appears something basic is either not working or some new feature is desperately needed. The air force expects to get the first MOPs for combat use by next year.
In the last few years several B-2 bombers have been equipped to carry these weapons (two bombs per B-2). This was apparently meant to send a message to Iran and North Korea. There were no other known targets for such a weapon but there are plenty of such targets in Iran and North Korea. Moreover, even were there deep bunkers in Afghanistan or Somalia, you don't need a stealth bomber to deliver a MOP there. The enemy in those countries have no way of detecting a high flying B-52, much less a stealthy B-2.
But Iran and North Korea do have air defense systems and a B-2 could slip past those radars and take out the air defense system command bunkers, or any other targets buried deep. The 6.2 meter (20.5 foot) long MOP has a thick steel cap and can penetrate 7.9-61 meters (26-200 feet) of concrete (depending on degree of hardness) or up to 61 meters of rocky earth, before exploding. The additional money may be needed to reconfigure, or reequip, MOPs with better penetration technology. Knowing that MOP exists, North Korea and Iran can add additional protection to their underground facilities.