The Pentagon has recently focused on developing and producing aviation bombs designed to destroy the enemy’s protected buried objects. 

To date, a relatively wide range of penetrating warheads and bombs based on them have been created. Such weapons are compatible with tactical and strategic aircraft, thus achieving high application flexibility.

Tactical level

Work on modern penetration/bunker bombs began in the mid-1980s. The first result from it soon became the BLU-109/B. It was a 2 kg (900 lb) unguided bomb for tactical fighters and bombers.

United States Bunker Buster Bombs
The fall and detonation of the GBU-24 bomb with BLU-109/B warhead

The BLU-109/B is made with a tough steel case with walls at least 1 inch thick. The inside was filled with 250 kg of explosives. Used for the lower fuse and tripped after a certain amount of time.

The bomb falls at high speed with the best launch conditions and gains much energy. So, the product can go through 1.8 meters of reinforced concrete or a few meters of soil.

Later, the BLU-109/B bomb’s warhead was used as a part of other weapons. With their help, they made changes to the guided bombs GBU-10 Paveway II, GBU-23, and GBU-27 Paveway III, etc. 

That made them better at getting through armor. The way these bullets were guided made it possible to use the warhead to its fullest potential. In the 1990s, the BLU-116/B pump was developed based on the BLU-109/B product.

A more durable alloy made of nickel and depleted uranium was used to make a new case. Keeping the same mass and wall thickness, this body made it possible to drill up to 3.4 m of reinforced concrete and then break down the bunker.

The new type of warhead could be employed as an unguided bomb and as corrected ammunition.

The BLU-118/B bomb was also used to make the BLU-109/B bomb. It has a similar body but a thermobaric warhead instead of a conventional one. A 254 kg load more effectively hits people and different things inside a buried target.

The BLU-109/B bombs have been being phased out in favor of the newer BLU-137/B bombs in recent years. Proven technical solutions were used in their creation, just like earlier projects, but they were applied with novel materials and components. The result was an improvement in several aspects.

B61 Mod.11 ammo has a coveted spot in the stockpiles. The yield of this tactical thermonuclear weapon can be adjusted from 10 to 340 kiloton-ton. The strengthened body can pierce several meters of dirt or concrete.

Several sources claim that the B61 Mod.11 is comparable to the non-nuclear BLU-116/B. Quite some time ago, developers finished up on an updated version of Mod.12. It can hit its target with greater precision and depth.

large caliber

During Operation Desert Storm, a peculiar piercing bomb was developed in a matter of weeks. After the commencement of hostilities, it became clear that the BLU-109/B product could not successfully engage certain of the enemy’s intended objectives. Here, the Pentagon issued an urgent directive to create new ammunition designated as the GBU-28.

This bomb weighed 5,000 pounds (2,270 kg) and contained 286 kg explosives. Stocked 203mm howitzer barrels were used to make durable cases for the first batch of weapons.

In the future, a hardened case with a special design will be added to the series. Such a warhead was designated BLU-113/B. It was suggested that a laser or satellite reference head be added. 

Tests showed that both versions of the GBU-28 bomb could go through at least 6.7 m of reinforced concrete. In the military, the GBU-28 airborne bomb was rarely used. Meanwhile, they proved the effectiveness of heavier ammunition, which led to the decision to create additional items of this type.

It was recommended to use new means of guidance and to enhance the range of aircraft carriers to boost combat characteristics. As a result, some of the new bombs were designed for B-2 and B-52 bombers.

Around the middle of the 1990s, the GBU-37 bomb came out. It was a much more modern version of the GBU-28, but it still had a BLU-113/B warhead.

It was added to by a modern GOS that was more accurate and based on satellite navigation. Because of this, the warhead could do more of what it could do.

Since the beginning of the ’50s, a more powerful anti-bunker ammunition called GBU-6.2 has been developed.

This product is about 800 m long and 30 mm wide. Caliber is 13,600 pounds, which is about 2.4 tons, and a load of 60 tons. Long-range bombers can only use this kind of bomb because it is so big.

It is said to be able to go more than XNUMX m deep. The GPS is used to give directions. The GBU-57 bomb has been improved several times so far. Their goal was to make the warhead more powerful and make it easier to hit its target.

Development Perspective

With new designs and materials, penetrating bombs gradually got better at fighting.

In just a few decades, American gunsmiths were able to make guns that could hit targets tens of meters away. But these successes didn’t make people stop going in that direction. The process of making new weapons that can destroy buried underground structures is still going on.

United States Bunker Buster Bombs
Promising ammunition GBU-72

The success of materials science in the building field is the reason for this kind of work. In the last few decades, new types of reinforced concrete have been made that are more resistant to damage from movement.

Different fillers, like thin metal wires or bigger pieces, are added to the concrete mix. Experiments that have been done show that the strength is much higher than “normal” reinforced concrete.

The GBU-72 ammunition is now being made to improve the existing aerial bombs and take out more difficult targets.

Last year, this pump was tested for the first time and showed what it could do. It is expected to go through all stages and be used shortly.

The Advanced 5K Penetrator, which is what the GBU-72 is called, is an improved 5-pound penetrating bomb. It looks like the old anti-bunker ammunition, but it is made of different material and has a different hull design.

It has been said that core features will improve, but we don’t know which ones yet. Different estimates say that penetrating bombs are close to reaching their full potential, but their future is uncertain.

Modern, high-tech building materials and techniques make it possible to again make buried objects safer. In particular, the idea that kinetic energy builds up when something falls puts some limits on development.

Different missile systems with the right warheads can be used with penetrating bombs to hit harder and more complex targets.

There is a lot of hope for hypersonic systems in this area. The weapon’s hardened warhead can go through a thicker layer of dirt and hit the concrete bunker underneath.

Several different kinds of hypersonic systems are being worked on simultaneously in the United States. It is unclear whether they will also be used to fight bunkers.

At the same time, the Pentagon knows that Russian hypersonic weapons have been used similarly, so it is likely to jump to conclusions.

United States Bunker Buster Bombs
GBU-57 bomb and its creators

Ample Opportunities

So, US long-range and tactical aviation has a pretty wide range of bombs that can be used to destroy underground structures with protection.

The samples in service work with different platforms and have different qualities. This lets you pick the best weapon for a particular target and improve other parts of the airstrike.

Bunker buster bombs are still being made better, and a new model will be used in the near future.

At the same time, it’s not clear what the future holds for this direction. The Pentagon may keep working on it and make new and better bombs. But in the future, they could be joined by more powerful weapons of destruction, making aviation a more powerful fighting tool.