What Are GBU-57 'Bunker-Buster' Bombs Used In US' Unprecedented Strike On Iran's Nuclear Facilities

The GBU-57A/B Massive Ordnance Penetrator (MOP), a 30,000-pound precision-guided "bunker-buster" bomb, was deployed by the U.S. in its Sunday airstrikes on Iran's Fordow nuclear facility. This marked the bomb's first operational use, targeting Iran's most fortified nuclear site buried deep beneath a mountain.

Key Features of the GBU-57

Design and Capabilities:

Weighing 30,000 pounds (13,600 kg) and measuring 20.5 feet long, the bomb uses a high-density steel-alloy casing and an ogive-shaped nose to penetrate up to 200 feet (60 meters) of reinforced concrete or bedrock before detonating.

Its 5,300-pound explosive payload (a mix of AFX-757 and PBXN-114) delivers kinetic energy comparable to a 565-ton train at 120 mph, concentrated into a tiny impact area for maximum destruction.

Guidance combines GPS and inertial navigation systems, allowing precision targeting within meters of the intended site.

Aircraft Compatibility:

Exclusively deployed by B-2 Spirit stealth bombers, which can carry two MOPs per mission. The B-2's radar-evading design (with a radar cross-section akin to a small bird) and 6,000-nautical-mile range enable deep-penetration strikes in contested airspace.

Role in the Iran Strike

Mission Execution:

Six GBU-57 bombs were dropped on Fordow by B-2 bombers, supplemented by 30 Tomahawk missiles targeting Natanz and Esfahan facilities.

The bombs were chosen specifically to destroy Fordow's mountain-buried enrichment plant, which conventional weapons could not reach.

Strategic Significance:

The MOP's use avoided nuclear escalation while fulfilling the U.S. military's objective of eliminating hardened weapons facilities. President Trump declared the strike "spectacularly successful," noting Fordow was "gone".

This deployment demonstrated the bomb's real-world efficacy against deeply buried targets, a capability developed to address post-9/11 bunker-destruction challenges.

Technical Controversies

Penetration Claims:

While the U.S. Air Force asserts the MOP can penetrate 200 feet of concrete, independent analyses suggest lower performance (e.g., 60 feet into 5,000-psi concrete).

The bomb's effectiveness relies on impact velocity (exceeding Mach 1) and sectional density to concentrate force during penetration.

GBU-57 is a milestone in conventional bunker-busting technology, combining unprecedented destructive power with precision delivery to neutralise Iran's most secure nuclear assets.