Subterranean Warfare – An Pressing DoW Want With out An Proprietor – The Cipher Temporary

The DoW urgently wants to prepare its scattered subterranean warfare belongings right into a single unified group. Ideally, a Direct Reporting Portfolio Supervisor (DRPM) for Subterranean Warfare, reporting to the Deputy Secretary of Battle. (The Division already makes use of this mannequin for unmanned methods, essential weapons and Golden Dome.) This group would have three portfolios: Subterranean Resilience, Subterranean Sensing and Subterranean Defeat. The workplace would combine validated necessities, experimentation, testing, acquisition, and fielding.

Subterranean Resilience

In the course of the 2026 Iran battle, Iranian ballistic missiles and low-cost drones hit U.S. installations throughout eight Center Japanese international locations. Lots of of buildings and constructions have been broken or destroyed. The Navy’s Fifth Fleet headquarters in Bahrain was among the many installations hit onerous. Iranian weapons broken one E-3 airborne early-warning plane and 5 KC-135 tankers on the bottom in Saudi Arabia. (The official inspector-general report paperwork the harm.) Regardless of 1000’s of profitable interceptions, the assaults uncovered the vulnerability of concentrated, above-ground belongings.

The speedy redeployment of the B-1s from RAF Fairford within the UK after warnings of an Iran-linked risk (reported as a doable drone assault) made the purpose: unsheltered concentrated high-value plane are weak even method outdoors the theater.

The assumptions the U.S. has made about air superiority, missile protection, plane dispersal, constructing hardening, and the survivability of concentrated ahead bases have been all flawed. Whereas we have been ready for ballistic missiles and hostile plane, drone swarms mixed with ballistic missiles saturated and bought via our defenses.

Washington’s response has been to take a position billions of {dollars} in counter-drone and missile protection methods. But public finances paperwork reveal no comparable effort to place weak plane, gas, command-and-control nodes, and munitions out of hurt’s method – sheltered, underground (or in area). (Agile Fight Employment, dispersal, hardening, deception, shelters, and speedy runway restore have been by no means designed for a mixed drone and missile onslaught.)

The Pentagon has acknowledged for many years that underground amenities are among the many best methods an adversary can blunt U.S. typical superiority. It described that drawback explicitly in 1999. Gaza and Ukraine ought to have made it abundantly clear.

China, Russia, North Korea, and Iran use underground amenities, dispersal, hardening, and deception to make their very own high-value belongings tougher to search out, assess, and disable. We have to underground belongings that can not be shortly changed: command posts, comms nodes, ammunition, gas distribution factors, restore amenities, key energy methods, upkeep spares, and high-value plane or drones. The division wants an integrator that coordinates resilience throughout the Army Departments, Joint Workers, combatant instructions, protection companies, and intelligence group and supplies Subterranean Resilience.

Nonetheless, resilience is just one a part of subterranean warfare.

Subterranean Sensing and Defeat

The U.S. must know the place adversaries’ underground amenities are situated, and the inner format of these amenities. At the moment, these bespoke beautiful methods for tunnel detection, robotic mapping of accessible tunnels, Arduous and Deeply Buried Targets (HDBT) characterization, and goal defeat are siloed in organizations scattered throughout the DoW. Most of those methods nonetheless require boots on the bottom. As soon as a goal is discovered, Combatant Instructions want an built-in system that may characterize and destroy these targets, with out first gaining bodily entry. At the moment, for the deepest amenities meaning bombing from the air. Iran is the living proof.

Background. Iran’s path to a nuclear weapon is by enriching uranium. Pure uranium consists of 0.71% uranium-235 (U235) and it’s solely the U235 that’s used to construct a bomb.

Iran makes use of centrifuges to separate U235 and enhance its focus (enriching it.) One centrifuge received’t do a lot, however connecting 1000’s of centrifuges collectively into cascades and working them for months can produce kilos of U235.

Iran’s underground nuclear enrichment website at Natanz had properly over 10,000 centrifuges put in throughout dozens of cascades, and their Fordow nuclear enrichment website was constructed for 16 cascades, roughly 3,000 machines. Earlier than the June 2025 strikes, Iran’s three declared enrichment amenities contained greater than 20,000 centrifuges in 125 full-sized cascades.

The tough estimate wanted for one Iranian nuclear weapon is ~100 lbs of U-235 at 60% enrichment or 55 lbs of U-235 at 90% enrichment (fashionable designs use much less.) The distinction is necessary, the lighter the weapon the simpler it’s to suit on a missile.

At its peak (Feb 2025 to June 2025) Iran’s cascades have been delivering ~86 lbs of uranium enriched to 60% which is about 50 lbs of U-235 monthly, which is just below one potential weapon each month. (Most weapons use U235 enriched to 90+% as a result of that allows a smaller, extra dependable design. Attending to that stage in Iran may take days or even weeks working the cascades, however constructing it right into a weapon would nonetheless be wanted.)

Deeply Buried Targets Versus Bunker Busters. One of many acknowledged targets of the U.S. strikes on Iran was to take away their capability to construct nuclear weapons. This required the U.S. to destroy their deeply buried underground nuclear enrichment websites. The most important typical bomb within the U.S. army’s arsenal is the 30,000-pound GBU-57 Large Ordnance Penetrator, carried by the B-2 Bomber. A 2019 description stated it might attain targets so far as 200 ft underground (its precise effectiveness relies on geology, concrete, facility design, entry factors, and using a number of weapons). The Iranians knew this and constructed their nuclear enrichment websites underground. The Fordow website is ~260 to 300 ft beneath limestone and dolomite. The Natanz website is 25 to 160 ft underground, protected by a 25-foot concrete defend. (However public estimates are over the place.)

Iran declared Isfahan as an enrichment complicated to the IAEA the day earlier than the June 2025 strikes; inspectors by no means bought inside it, subsequently its depth and geology are unknown, however hypothesis is that the enrichment complicated is 260 to 330 ft underground. One other suspected enrichment facility is in Pickaxe Mountain, the place the precise depths, geology, are unknown however estimates put the ability 250 – 330 ft beneath the summit. Each Isfahan and Pickaxe have been Iran’s shift towards “deep mountain basing” to flee the attain of typical army strikes.

In June 2025 in Operation Midnight Hammer U.S. B-2 bombers dropped 14 GBU-57 bombs on prime of Fordow and Natanz. At Isfahan (Esfahan) greater than two-dozen submarine-launched Tomahawks hit tunnel entrances and floor targets. In March 2026, strikes at Natanz hit its entrance.

In line with the Institute for Science and Worldwide Safety, the 22,000 centrifuges at Natanz, the Natanz pilot plant, and Fordow are virtually definitely wrecked. What could have survived is the enriched uranium, the spare elements, and the folks, and that’s the drawback. The Worldwide Atomic Vitality Company estimated (in June 2025) that Iran had about 970 kilos of uranium enriched to 60%; it has since misplaced monitor of the place it’s. Iran’s identified uranium conversion functionality at Isfahan was broken, which it wanted to show the stockpile of enriched uranium right into a weapon, and there’s no public proof that enrichment has resumed at Natanz, Fordow or Isfahan. We by no means hit Pickaxe Mountain or the Isfahan enrichment facility with the GBU-57. The strikes have set Iran again, however nobody is aware of for a way lengthy.

Whereas the GBU-57 MOP can’t cleanly punch via strong rock, the controversy has shifted from an absolute bodily destruction calculation to a useful denial calculation—which means the army’s aim could be to seal Iran’s nuclear belongings in a mountain tomb moderately than blowing them up straight.

Did We Succeed? Our acknowledged aim was to forestall Iran from quickly rebuilding the aptitude to construct nuclear weapons, however there’s no certainty that we did that. Repeated airstrikes could have broken the buried enrichment vegetation, however we will’t show it or account for the buried enriched uranium inside. The actual fact is that it’s extraordinarily troublesome to see how a lot harm the bombs did to Arduous and Deeply Buried Targets (HDBTs) from the air, and with out inspectors on the bottom, understanding for certain is guesswork. Placing boots on the bottom would carry huge prices and dangers. Negotiating the elimination and inspection of weapons grade uranium would rely upon Iranian cooperation and a strategy to confirm we bought all of it. All dangerous decisions.

There’s one other rising choice: autonomous drilling tools.

Subterranean Sensing and Defeat. It’s not onerous to think about that with sufficient boots on the bottom the U.S. might safe a touchdown zone, fly in drilling tools and have crews drill lots of of ft vertically or 1000’s horizontally to both place sensors and/or explosives. The U.S. has had organizations constructing specialised tools and coaching for breaching tunnels in Combatant Instructions and scattered throughout the DoW for years (DTRA, DARPA, Military ERDC and CAVES and CZ5 applications, SOCOM, Sandia and the Military’s half-billion-dollar underground-training push (2018) and ATP 3-21.51 Subterranean Operations.) One may even think about that there are groups already skilled and tools prepared to go. And one can equally think about the Iranians are ready for them.

What’s new is autonomous drills that might present post-strike bomb harm assessments and/or destroy Arduous and Deeply Buried Targets (HDBTs) with out seizing the positioning. They is likely to be inserted covertly; extra doubtless they’d want air cowl whereas they work.

The mix of AI, robotics and autonomy strikes this from science fiction to the doable.

Anduril, The Boring Firm, Exodigo, Phoenix Boring, Earthgrid and Traysar are doable candidates to ship these methods. There are doubtless others as properly.

(Disclosure: after my first weblog about undergrounding essential belongings, I invested and have a monetary curiosity in corporations on this area.)

Floor survivability and subterranean sensing and defeat are not one Service’s drawback, and so they will not be solved by a single system or an incremental repair. One thing basically disruptive has modified within the nature of uneven warfare and there’s no going again. Whereas we’re actively chasing rapid options (Golden Dome, JIATF-401, et al), we have to rethink the character of pressure safety, and army and civilian infrastructure safety.

The U.S. wants a coherent safety and survivability technique throughout the DoW and all sectors of our economic system. This dialog must be not solely about how we do it, however how we set up it, how we finances and pay for it, and the way we quickly deploy it.

The Cipher Temporary is dedicated to publishing a variety of views on nationwide safety points submitted by deeply skilled nationwide safety professionals. Opinions expressed are these of the creator and don’t symbolize the views or opinions of The Cipher Temporary.

Have a perspective to share primarily based in your expertise within the nationwide safety subject? Ship it to Editor@thecipherbrief.com for publication consideration.

Learn extra expert-driven nationwide safety insights, perspective and evaluation in The Cipher Temporary