MOP is a GPS-guided, earth-penetrating strike weapon for use against hardened and deeply buried targets. It was developed and tested through a USAF and Defense Threat Reduction Agency partnership in 2004 and is now managed by AFGSC. Flight-testing was conducted from 2008 to 2010, when the program transitioned to USAF.
A B-2 successfully test-dropped the GBU-57 in 2014, 2015, and 2016. Several B-2s completed a total of four test drops at White Sands Missile Range, N.M., in 2017, validating the effectiveness of mods made under the Enhanced Threat Response IV upgrade.
MOP proved effective, clearing the way for potential early fielding, though the Air Force’s recommendation was classified. The service is currently testing the Large Penetrator Smart Fuse (LPSF) to increase precision and lethality, though delays constructing representative test targets have pushed potential fielding of the upgrade to FY25 or beyond.
A B-2 employed an LPSF-equipped weapon against a tunnel test target in 2020 to validate the design, followed by a series of three performance test drops between August 2021 and May 2022. USAF conducted two full-scale tests in 2024 to validate B-2 integration fixes and Smart Fuse functionality, as well as lethality.
B-2s struck three Iranian nuclear sites with 14 MOPs, marking the weapon’s first operational use during Operation Midnight Hammer in the early morning of June 22, 2025. All weapons functioned as designed, causing severe damage to the facilities and validating recent modifications made to the weapon, concluding testing.
GBU-57 Massive Ordnance Penetrator (MOP) Technical Data
Contractor: Boeing.
First Flight: 2008.
IOC: 2011.
Operator: AFGSC.
Active Variant: •GBU-57B. GPS-guided 30,000-lb penetrating weapon.
Guidance: GPS.
Warhead: 5,740-lb HE.
Dimensions: Length 20.5 ft, diameter 31.5 in.
Integration: B-2A (tests also conducted on the B-52).