After nearly a decade of development, the U.S. Air Force has ordered eight MOP (massive ordnance penetrator) GBU-57A/B bunker buster bombs. These 14 ton weapons cost $3.5 million each. 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.
Pucker factor? Very high in Pyongyang and Tehran.
