Air Force wants to replace the world’s strongest bunker buster… with an even stronger one

Airpower

By Alex Hollings

July 23, 2025

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The United States recently announced a replacement for its GBU-57 MOP, or Massive Ordnance Penetrator, which is the largest bunker buster ever fielded.

The MOP went viral in recent weeks after 14 of these 30,000-pound weapons were dropped by seven B-2 Spirit stealth bombers over Iran’s underground nuclear enrichment facilities in Natanz and Fordow.

The GBU-57 is rated to penetrate upwards of 200 feet of earth or more than 25 feet of steel-reinforced concrete. In the attack against the Iranian underground facilities, the U.S. Air Force layered these strikes on top of one another to increase the munition’s maximum penetration depth.

However, for the future, the Air Force wants an even more capable bunker buster – and this is currently being developed under the name of “Next Generation Penetrator,” or NGP.

According to an Air Force contracting notice released in February 2024, this new weapon is expected to carry a warhead of less than 22,000 pounds, though no weight requirement was listed for the overall weapon’s combined weight. The weapon is also expected to offer greater accuracy, even in GPS-degraded or denied environments.

Maybe most notable of all, the notice also highlights the Air Force’s interest in a powered stand-off capability for this new bunker buster. This means that the weapon itself would have propulsion that can carry it to its target over some distance, allowing bombers to drop it from safer distances. And as expected, this new weapon is intended to offer even greater penetration capabilities than the latest iteration GBU-57, which has a classified maximum depth rating.

Feature Image: MOP being offloaded in preparation for its first explosive test, 2007. (Creative Commons)