Will Trump’s bunker buster bombs punch through Iran’s Pickaxe Mountain?
Conventional bombs explode on or near a target surface, with the explosion and fragments, e.g. shrapnel, rendering the bomb’s damage. But when a target is
Conventional bombs explode on or near a target surface, with the explosion and fragments, e.g. shrapnel, rendering the bomb’s damage. But when a target is buried deep under a mountain, the soil and rock mass surrounding it can absorb enough of the blast’s energy to keep the target from being damaged too much. This is the situation facing the Donald Trump administration as it mulls plans to bomb Pickaxe Mountain in Iran, where The Wall Street Journal has reported Israel believes Tehran has moved several centrifuges — the machines that purify uranium to make an a-bomb. Bunker buster bombs The need to bomb targets under a thick layer of earth led scientists to invent bunker buster bombs. Instead of exploding when they come in contact with the earth, these bombs are designed to penetrate soil, rock, and even reinforced concrete before detonating. The U.S.’s most powerful conventional bunker buster is the GBU-57A/B Massive Ordnance Penetrator, shortened to MOP. The world’s largest non-nuclear bomb, a single MOP weighs around 13.6 tonnes and is currently delivered only by the U.S. Air Force’s B2 Spirit stealth bomber. The MOP entered combat for the first time during the U.S.’s June 2025 strikes against Iran in the 12-Day War. The MOP does not drill through rock. Instead, it uses an enormous amount of kinetic energy to punch its way through. The B2 Spirit can cruise at an altitude of 50,000 ft. When a 13.6-tonne object is dropped from that height, it will have a theoretical maximum kinetic energy of 2 gigajoules (GJ) when it reaches the ground — about as much energy with which American Airlines Flight 11 smashed into North Tower on 9/11 — and at a speed of nearly 2,000 km/hr. In reality, the MOP will face significant atmospheric drag and, from that altitude, will reach the ground at 1,000-1,300 km/hr, with a kinetic energy of 0.6-0.8 GJ. This is still equivalent to the energy released by detonating around 170 kg of TNT. And to ensure this helps the MOP get as close to the target as possible, it features a hardened steel casing, a nose only a few tens of centimetres across, and a delayed fuse that kicks off only after the bomb has burrowed underground.
If the MOP has a kinetic energy of 0.7 GJ, a nose 20 cm wide will exert a pressure 2.1-lakh-times the atmospheric pressure, and if it’s able to penetrate 1 m of rock, a force equivalent to 71,000 tonnes under earth’s gravity. If multiple MOPs are dropped in sequence over the same point, each one can penetrate deeper than the last. Cost of making an MOP The unit cost of an MOP is not available in the public domain but estimates in the media suggest $15-20 million per bomb. The need for multiple bombs may also weigh heavily on the U.S. government’s mind in terms of their demand for critical minerals. As researchers from the Payne Institute of Public Policy wrote in March this year, “The biggest issue for the [American] defense industrial base will be sourcing the 77.3 kg of gallium needed” to rebuild the advanced radars in Bahrain and Qatar damaged by Iranian missiles, “a material for which China controls 98% of the global supply. … As the long conflict in Ukraine has already illustrated, war is being costed in the wrong units. The relevant metric is not merely how many launchers there are at the start of the war, but how many precision weapons and interceptors can be fired on days two, 20, and 200, and how quickly industry can replace them.” Again, while a bill of materials isn’t available for the MOP, a survey of other precision-guided penetrators suggests each bomb may include up to a quintal of tungsten, tens to hundreds of grams of rare-earth elements, and several other critical minerals of varying quantities in between. Bomb versus mountain For all the impressive forces the MOP is capable of, a mountain can be much more formidable. Iran hasn’t released geological surveys of Pickaxe Mountain — which locals know as Kuh-e Kolang Gaz La. But the Karkas Range that it is part of is predominantly volcanic in origin, with surveys indicating it consists mainly of volcanic rocks from the Eocene period. Volcanic rocks like andesites and rhyolites are generally hard and difficult to excavate.
The BriefWire