In 2002, Northrop Grumman and Lockheed Martin were working on the development of a 30,000-lb (13,600 kg) earth-penetrating weapon, said to be known as "Big BLU". But funding and technical difficulties resulted in the development work being abandoned. Following the 2003 invasion of Iraq, analysis of sites that had been targeted with bunker-buster bombs revealed poor penetration and inadequate levels of destruction... This renewed interest in the development of a super-large bunker-buster, and the MOP project was initiated by the Defense Threat Reduction Agency to fulfill a long-standing Air Force requirement.
The U.S. Air Force has not officially recognized specific military requirement for an ultra-large bomb, but it does have a concept for a collection of massively sized penetrator and blast weapons, the so-called "Big BLU" collection, which includes the MOAB (Massive Ordnance Air Burst) bomb. Development of the MOP is now underway at the Air Force Research Laboratory, Munitions Directorate, Eglin Air Force Base, Florida. Design and testing work is also being performed by Boeing. It is intended that the bomb will be deployed on the B-2 bomber, and will be guided by the use of GPS.
Northrop Grumman announced a $2.5-million stealth-bomber refit contract on 19 July 2007. Each of the U.S. Air Force's B-2s is to be able to carry two 14-metric-ton MOPs.