The enormous munition—previously used against Iran’s nuclear facilities during “Operation Midnight Hammer” in June 2025—was reportedly used to target an underground Iranian leadership meeting in Tehran.

Operation Epic Fury is still underway, and in spite of the destruction of much of Iran’s leadership echelon, Tehran continues to put up stiff resistance. Accordingly, the US military is bringing out the biggest weapons in its arsenal in an attempt to force Iran’s remaining leaders to the negotiation table. 

As part of the strategy of steadily increasing pressure on the Iranian regime, the US Air Force reportedly dropped the GBU-57 Massive Ordinance Penetrator (MOP), its biggest non-nuclear bomb, against a regional headquarters of the Islamic Revolutionary Guard Corps on Monday.

CENTCOM Planned the GBU-57 Strike Many Hours in Advance

US Central Command (CENTCOM) had actionable intelligence that a large number of senior Islamic Revolutionary Guard Corps leaders would be meeting inside an underground bunker in Tehran, according to The Wall Street Journal. 

The B-2 fleet operates from Whiteman Air Force Base in Missouri. Each mission involves a round-trip of nearly 14,000 miles. 

This was a dynamic mission based on incoming intelligence. Because the B-2 has to fly from the US for every mission, it is likely that CENTCOM had notification of the upcoming meeting—or even had B-2s equipped with the specialized munitions on call in the event of a high-value target. 

This is the second time that B-2s have dropped GBU-57 MOPs over Iran. Last summer, during Operation Midnight Hammer, B-2s bombed two of Iran’s most guarded nuclear weapons facilities, dropping several GBU-57 MOPs onto each.

Which Aircraft Can Carry the GBU-57 Bunker-Buster Bomb?

The B-2 Spirit stealth strategic bomber is the only aircraft in the US fleet that can carry the munition. Indeed, its weapon bays are so spacious that it can carry two GBU-57 MOPs. Although the Air Force did some tests to determine whether the B-52 Stratofortress could carry the massive munition, there would need to be considerable alterations on the structure of the aircraft to be able to carry the bomb.

In the future, the B-21 Raider, which is undergoing flight testing and will soon enter full-scale production, is expected to be able to carry at least one GBU-57 MOP. 

About the GBU-57 Bunker-Buster Bomb

• Length: 20.5 feet (6.2 m) 
• Diameter: 31.5 inches (~0.8 m) 
• Total Bomb Weight: ~30,000 lbs (~13,600 kg) 
• Explosive weight: ~5,300 lbs (~2,425 kg) of high explosives, including:
  • AFX-757: ~4,590 pounds (~2,080 kg) 
  • PBXN-114: ~750 pounds (~340 kg) 
• Targeting: GPS/INS guided with a 20-foot circular error probable 
• Penetration Capabilities: At least 200 feet (60 m) of earth and/or hardened concrete 

The GBU-57 MOP is the largest non-nuclear munition in the US military’s arsenal. 

“The Massive Ordnance Penetrator (MOP) is a weapon system designed to accomplish a difficult, complicated mission of reaching and destroying our adversaries’ weapons of mass destruction located in well protected facilities,” the Air Force states in the mission profile of the munition. 

The munition is designed to penetrate hardened deep underground targets. The bomb’s hardened casing is intended to penetrate the first layer of the hardened target, whether it is a bunker or a facility deep underground. Next, the 5,000-pound warhead detonates, causing catastrophic damage to the target—significantly amplified by the enclosed space. Depending on the target, the B-2 will drop additional bombs on the channel created by the first munition for a devastating effect on the target.

About the Author: Stavros Atlamazoglou 

Stavros Atlamazoglou is a seasoned defense journalist specializing in special operations and a Hellenic Army veteran (national service with the 575th Marine Battalion and Army HQ). He holds a BA from the Johns Hopkins University and an MA from the Johns Hopkins’ School of Advanced International Studies (SAIS). His work has been featured in Business Insider, Sandboxx, and SOFREP.

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