GBU-57A/B, the powerful bomb “Rompebúnkeres” that US used against Iran’s nuclear facilities

Image source, US Air Forces

- Author, Luis Barrucho
- Author’s title, BBC News
June 22, 2025

Updated 7 hours

Among the weapons capable of attacking the underground nuclear facilities of Iran, there is one that used the US in the early hours of this Sunday: the massive of mass ammunition (MOP) GBU-57A/B, the largest non-nuclear bomb “Rompebúnkers” of the world, exclusive property of Washington.

High officials of the Department of Defense confirmed the use of this guided weapon with precision, of 13,600 kg of weight, something that the Pentagon also did on Sunday morning.

It was confirmed that it is the first time this pump is used.

USA said that Iran’s nuclear program had been “destroyed”, but Iranian television said the damage was not important and that the bases had been previously evacuated.

According to the US government, the GBU-57A/B is a “great penetrating weapon with the capacity to attack bunkers and tunnels built at great depth and fortified.”

With six meters in length, it is believed that it is able to penetrate approximately 61 meters under the surface before exploiting. Several pumps can be launched, drilling even more with each explosion.

Manufactured by Boeing, the MOP has never been used in combat, but has been tested in the White Sands missile field, a US military trial zone located in the state of New Mexico.

It is more powerful than the Massive Ordnance Air Blast (Moab), a 9,800 kg weapon known as “the mother of all bombs”, which was used in combat in Afghanistan in 2017.

A BBC graph shows the operation of the breaking. The graphics show their height (6.25 meters), their weight (13,600 kilos) and the depth to which the concrete can penetrate (60 meters).

Limited arsenal

“The US Air Forces struggled to devise weapons of a size very similar to the MOAB, but with the explosive load contained within an extremely hard metal box. The result was the GBU-57A/B Massive Ordnance Penetrator (MOP),” Paul Rogers, Professor Emeritus on Peace Studies at the University of Bradford (United Kingdom).

At present, only the American B-2 Spirit-also known as the poaching bomber-is configured and scheduled to launch the MOP.

The B-2, manufactured by Northrop Grumman, is one of the most advanced war planes of the Arsenal of the US Air Forces.

According to its manufacturer, the B-2 can transport a useful load of 18,000 kg.

Chart that shows how the GBU-57A/B pump works

However, US Air Forces claim that they have successfully tried that the B-2 can transport two GBU-57A/B, which is a total weight of about 27,000 kg.

This long -range heavy bomber has an autonomy of about 11,000 kilometers without replenishing, and up to 18,500 km with a replacement in flight, which allows it to reach almost any part of the world in a matter of hours, according to Northrop Grumman.

Rogers said that if the MOP was ever used against an enemy with modern aerial defenses, such as Iran, to the B-2 bombers would probably join F-22 furtive attack planes for the suppression of the defenses, followed by drones to evaluate the damage and determine if more attacks are necessary.

The expert calculated that the United States has a limited arsenal of these MOP pumps.

“They probably have an operational arsenal of about 10 or 20 of those pumps in total,” he said.

American military personnel handling a mass penetration pump (MOP) placed on a truck — Photo foot, It is believed that the MOP is able to penetrate about 61 meters below the surface before exploiting.

Ford

Fordo is Iran’s second nuclear enrichment installation after Natanz, the main one.

It is built on the slope of a mountain near the city of Qom, about 95 km southwest of Tehran. It is believed that it began to be built towards 2006 and that it came into operation in 2009, the same year in which Tehran publicly recognized its existence.

In addition to being buried about 80 meters under rock and land, Fordo is protected by Iranian and Russian Earth-Aire Missile Systems.

In March 2023, the International Atomic Energy Agency (OIEA) detected uranium particles enriched with a purity of 83.7%, almost suitable for armament, in the site.

“Our goal was the destruction of the enrichment capacity of Uranium of Iran and a stop to the nuclear threat raised by the sponsoring state of the world number one in the world,” Trump said this Saturday in a televised statement, after having announced the attack against Fordo and two other nuclear facilities, Natanz and Isfahán’s.

Iran has always said that its nuclear program is totally peaceful and that it has never tried to develop a nuclear weapon.

But, last week, the Board of Governors of the OIEA, formed by 35 countries, declared that Iran had breached its non -proliferation obligations for the first time in 20 years.