The world has only seen the "super bomb" GBU-57 once, but America wants to replace it.

During Operation Night Hammer, seven US B-2 Spirit stealth bombers dropped a total of 14 GBU-57 MOP bombs weighing nearly 14 tons on Iran's Fordow and Natanz nuclear facilities, of which the Fordow complex alone received 12 bombs.

With the ability to penetrate 60 meters into the ground, the GBU-57 "super bomb" is considered by some experts to be the only weapon that can penetrate the "nuclear fortress" Fordow, a facility built deep inside a rocky mountain in Qom province. This is the first time the GBU-57 bomb has been used in real combat conditions.

A GBU-57 bomb is loaded onto a B2 stealth bomber. Photo: USAF

In terms of power, functionality and technology, no country in the world currently possesses a similar bomb. However, as the United States, always leading in the field of military technology, they do not stop there.

Joseph Trevithick, a commentator for the military website War Zone , said that since the GBU-57 line was first deployed in the early 2010s, the US has been researching and developing a successor called the Next Generation Penetrator (NGP).

The project was last mentioned in a US Air Force tender notice in February 2024. The force said at the time that the NGP was expected to have a maximum warhead weighing about 10 tons, which is nearly four times the warhead of the GBU-57, and also have fragmentation and penetration capabilities.

Officially named the Next Generation Penetrator (NGP), this new-generation bunker-buster bomb will be compatible with the B-21 Raider bomber, the United States' next-generation stealth bomber planned to replace the B-2 Spirit bomber.

The NGP is envisioned as a more advanced version of the GBU-57 MOP. It can also have an attached rocket booster for long-range strike capability and precision strike capability within a Circular Error Probability (CEP) of 7.2 feet (2.2 meters), in both GPS-aided, degraded and denied environments.

Additionally, the United States Air Force (USAF) is also interested in the Global Precision Strike Weapon (GPAW) bunker-buster bomb, which is small enough to fit in the internal weapons bay of stealth fighters like the F-35.

The Air Force said it would receive about 10 miniature test models and three to five full-size warhead prototypes within 18 to 24 months of the contract award, but it is unclear when the contract will be awarded. Officials have also not announced a specific roadmap for when the NGP bomb will be put into service.

The moment B2 - Spirit drops GBU-57 bunker-piercing bomb. Photo: USAF

“However, the US military has demonstrated the value of the GBU-57 in real-world conditions,” Trevithick said. “This will likely increase interest in developing a successor, bringing more resources to the NGP project.”

The tender also mentions the possibility of “embedded fuze” technology, which seems to refer to the integration of the fuze into the bomb rather than as a separate component, which would provide better protection. A precise fuze is crucial for tunnel-penetrating bombs, as otherwise the bomb will detonate prematurely and not penetrate deep enough to the target.

Not only the detonator, other components of the penetrator bomb must also be durable enough to withstand the impact force when passing through layers of solid materials such as soil, rock, and concrete.

The US military has also been researching fuses in recent years that can determine when a projectile has penetrated a large area, such as a bunker in an underground facility.

This technology is similar to the Programmable Intelligent Multi-Function Fuze (PIMPF) on the German Taurus missile, which is capable of determining how many layers of material an object consists of and the gaps between the layers, thereby calculating the time of explosion to effectively attack the target.

“A fuze that can accurately ‘count’ the number of layers of material to determine the depth at which maximum damage is caused by detonation would be a useful addition,” Trevithick said.

The US Air Force has also mentioned the possibility of equipping the NGP bomb with an engine, giving the bomb long-range attack capability. Simulation drawings of the bomb show that it can be integrated with a rocket engine.

The GBU-57 is not powered and must be dropped close to the target, one of the reasons why only the B-2 bomber, which has high survivability thanks to its advanced stealth capabilities, is certified to use this type of bomb.

Trevithick said that having a long-range tunnel-penetrating bomb is very important for the US Air Force, in the context of the continuous improvement of air defense capabilities of other countries. This force assessed that air defense missiles with a range of 1,600 km are one of the threats they will have to face by 2050.

"Even advanced stealth aircraft like the B-2 and B-21 would face challenges attacking near well-defended critical targets of a peer opponent," the commentator said.

The Air Force also wants the NGP to penetrate deeper and more heavily fortified targets than the GBU-57, as well as have a greater destructive power in the terminal phase and be adjustable. While public documents show that the GBU-57 can penetrate at least 60 meters, it is likely that the penetrating power of this bomb has been significantly increased after undergoing many upgrades.

The US Air Force also raised the possibility that the NGP project would include different types of bombs. The NGP is also linked to the Long Range Strike System (LRS), whose most famous member is the "stealth killer" B-21, the successor to the B-2 bomber.