The GBU-57, also known as the "Massive Ordnance Penetrator" (MOP), is a United States Air Force bunker-busting bomb. It is considered the most powerful conventional (i.e. non-nuclear) weapon of its kind in the world and was specifically developed to destroy deeply buried underground targets. It is the only one powerful enough to destroy Iran's protected nuclear facilities.
According to President Donald Trump, the US carried out strikes on Iranian nuclear facilities overnight, including using B-2 bombers armed with GBU-57 bombs. Trump claims it was a "very successful strike" on three facilities - including the underground uranium enrichment facility at Fordow.
How was the GBU-57 constructed?
The GBU-57 is about six meters long and weighs more than 13 tons. Its casing is made of high-density reinforced steel, which can withstand extreme loads when penetrating concrete, rock or soil without bursting. Inside is a high-explosive explosive weighing about 2,4 tons. This means that it is one of the largest conventional weapons in the US military's arsenal, along with the GBU-43 "Massive Ordnance Air Blast" (MOAB), which is about nine meters long and weighs almost ten tons.
The GBU-43, also known as the "Mother of All Bombs", has even greater explosive power with 8,5 tons of explosives and a destruction radius of 150 meters, but unlike the GBU-57, it is not intended for penetrating bunkers, but for broadband destruction.
How does a bomb work?
The bomb is dropped from a high altitude from a B-2 Spirit bomber with reduced radar reflectivity technology. Controllable surfaces on the tail and a modern GPS system enable high accuracy of the hit. Due to its large mass and the speed it develops during flight, the bomb hits the target with enormous force and penetrates deep into the ground. Thanks to the so-called "smart fuze", which takes into account the depth and structure of the target, the bomb explodes only when it has penetrated deep enough to cause maximum damage.
What is the penetration power and explosive yield of the GBU-57?
The GBU-57 can penetrate up to 60 meters of reinforced concrete, eight meters of high-strength concrete, or 40 meters of rock before detonating. By comparison, the most powerful bunker-busting bomb in Israel's arsenal, the GBU-28, as well as the German-Swedish Taurus cruise missile, can only penetrate up to six meters of reinforced concrete.
Currently, the GBU-57 can only be carried and dropped by the US B-2 Spirit stealth bomber. A single B-2 can carry up to two such bombs. Its successor, the B-21 Raider, which is still in the testing phase, is expected to be capable of carrying the GBU-57.
The B-2 Spirit has so-called stealth technology, which makes it almost invisible to radar.
What are the costs – and how many are there?
One of the main disadvantages of the GBU-57 is that its production and use involve high costs and complex logistics. The price of one bomb is 3,5 million US dollars. Currently, the US Air Force has only 20 such bombs and 19 B-2 bombers that can use them. Therefore, the GBU-57 is used exclusively for strategically important targets.
Why is the GBU-57 so important to Israel's war against Iran?
One of Israel's main goals in the current war against Iran is to prevent Iran from developing nuclear weapons. That's why Israeli attacks in recent days have been directed not only at military targets, but also at facilities where uranium is enriched to weapons-grade levels.
One of the most important targets is the Fordo nuclear facility, estimated to be 60 to 90 meters below the surface, at the base of a mountain. The GBU-57 is the only conventional bomb that can penetrate deep enough to destroy the site.
Only the US Air Force has it. Israeli bunker-busting bombs do not have enough penetration power to destroy Iran's deepest nuclear facilities like Fordow. Furthermore, Israel does not have the B-2 bombers needed to use the GBU-57. Therefore, the country is completely dependent on US support to achieve its war goals.
Contradictory reports on the extent of destruction
While Trump claims the nuclear facilities have been "completely destroyed," Iran's state news agency IRNA reported that part of the area around the Fordo uranium enrichment facility had been damaged. It quoted a spokesman for the crisis management team in the affected Qom province as saying that the situation in those areas was now calm again.
A senior security official in Isfahan province also confirmed the attacks "near" the nuclear facilities in Isfahan and Natanz, according to the Tasnim news agency, which is close to Iran's Revolutionary Guard.
According to consistent reports in the US media, the US military used two bunker busting bombs in the attack on the Natanz nuclear facility. They were dropped from a B-2 stealth bomber. In addition, Natanz was attacked with cruise missiles launched from submarines.
At the same time, it was reported that six stealth bombers dropped a total of twelve of the US military's largest bunker-busting bombs on the underground Fordow nuclear facility. A third US target in Isfahan was reportedly attacked only with cruise missiles.
According to American reports, all aircraft involved in the attack safely left Iranian airspace.
US President Donald Trump warned Iran in a speech to the nation not to respond to these attacks, because, he said, there are other targets that could be attacked if Iran is not ready for peace. Future attacks will be far more severe, Trump said, stressing that Iran faces a choice between peace and tragedy.
Bonus video:
