Buried roughly 500 metres deep inside a mountain in central Iran, the Yazd missile base is less a bunker than a buried fortress.

Carved into one of the hardest types of rock on Earth, the facility sits inside Shirkuh granite that can withstand crushing pressures far beyond conventional construction materials.

This material puts up the toughest barrier possible for even the most powerful American bunker-busting bomb – the GBU-57 Massive Ordnance Penetrator.

And inside, the mountain has been hollowed into something closer to a hidden city than a military base. 

The secret facility is thought to possess an automated rail system which runs through tunnels linking assembly areas, storage depots and multiple concealed exits cut into different faces of the mountain.

In similar underground missile cities seen in Iranian propaganda videos, launchers are moved around rapidly on lorries, rolled out to fire, and withdrawn back underground behind heavy armoured doors in the blink of an eye.

Despite weeks of relentless US-Israeli strikes on its facilities, Iran is somehow still able to unleash its hidden arsenal of rockets and drones at targets across the Middle East.

According to the Institute for the Study of War (ISW), the Yazd missile base alone is thought to have been hit at least six times since the start of Trump’s war with Iran, including on March 1, March 27 and 28. 

A handout photo made available by the Iranian Army in 2022, shows drones in an underground drone base, in an unknown location in Iran

Yet footage published by an OSINT (open source intelligence) account on March 28 appears to show two missiles being launched from the site, ISW reports.

However it remains unclear whether the launches took place before or after the US-Israeli strikes.

Across Iran, similar underground ‘missile cities’ have reportedly been carved into mountains, forming a dispersed web of hardened sites that support the country’s ballistic missile capability.

The Islamic Republic has spent years constructing these cavernous bunkers to shield its vast missile arsenal from destruction, experts say.

And while Israel pummeled Tehran’s infrastructure in June’s 12 day war, the regime emerged from the bruising conflict with much of its stockpile of thousands of ballistic missiles intact.

Now, US intelligence sources have claimed that Iran still has half its missile launchers and of thousands of drones.

Three well-placed sources told CNN that the latest American intelligence assessments indicate Iran retains significant firepower.

The estimates may include launchers that are inaccessible, such as those that have been buried by strikes, but not destroyed.

Iran still has access to roughly half of its original drone stock, two of the sources suggested, which would number well into the thousands.

A large proportion of its coastal defence cruise missiles, the weapons that allow Iran to threaten traffic in the Strait of Hormuz, are also thought to remain intact.

Israel estimated Iran to have had around 470 ballistic missile launchers at the beginning of the war, and last month claimed to have destroyed or disabled around 60 percent of them.

Since the start of the current conflict, US and Israeli forces have carried out an extensive campaign targeting Iran’s missile infrastructure.

Across the country, strikes have collapsed entrances, cratered ventilation shafts and damaged surface installations. However, the system deep underground remains intact.

A recent CNN investigation, found that while 77 per cent of visible tunnel entrances had been hit, activity at those sites resumed quickly.

Construction equipment was observed returning within days, clearing debris and reopening access routes into the mountains.

Reports describe cavernous halls filled with ballistic missiles, drones and launch systems, all believed to be connected by transport corridors designed for rapid movement.

A report by Alma Research found similar data in its January 2026 assessment based on damage sustained during the 12 day war in June.

This image from 2022 released by the Iranian Army shows an underground bunker full of drones in an unknown location

Iran showed off a sprawling underground network of tunnels filled with row after row of drones and rockets in a propaganda video at the start of the war

Footage released by Iran’s Fars News Agency a week into the current conflict showed long rows of missiles and Shahed drones lined up inside one such facility, with trucks carrying launchers positioned deep within the tunnels.

Iranian flags hung from the ceilings as the camera moved through the space, revealing the concerning scale of what has been built out of sight.

Many of the drones are relatively cheap and quick to produce, while the systems used to intercept them are far more expensive.

Defending against such attacks can cost many times more than launching them, raising concerns that even well-equipped adversaries could face strain over a prolonged campaign.

However, experts say the real difficulty lies in penetrating the carefully-designed architecture where the weapons are stored. 

These underground complexes are designed around resilience, with tunnels segmented with blast-resistant doors to contain damage.

Multiple entrances and exits allow operations to continue even if one or several access points are destroyed.

Meanwhile, some openings are decoys and others are concealed within the natural contours of the terrain, making them difficult to identify and target.

And even the most advanced bunker-busting weapons are constrained by the material they must penetrate.

Speaking to the Statesman, analyst Shanaka Anslem Perera said: ‘The mountain does not care how many sorties are flown above it. 

‘The railway does not care how many portals are sealed. The geology is the defence, and the geology has been there for 300 million years.’ 

Penetration depth varies depending on whether a target is covered by soil, concrete or dense rock.

Granite, in particular, absorbs and disperses explosive energy, reducing the effectiveness of even the largest conventional munitions.

According to RUSI, penetrating hardened underground facilities may require multiple strikes on the same point, detailed intelligence on internal layouts and sustained follow-up attacks to prevent rapid repair.

And all of this must be carried out while suppressing air defences and coordinating attacks across multiple dispersed sites.

Speaking to Globes, tunelling expert Dr Amichai Mittelman said: ‘The mountains in Iran provide a level of protection 50-100 meters thick of rock that is hard to crack even by heavy bombs.’

Targeting entrances has its limitations, as destroying an opening can block access temporarily, but does not collapse the network behind it.

The same logic applies to other potential weak points, such as ventilation holes.

‘The Iranians thought of everything, so they built many ventilation holes and shafts and installed fans to compress the air inside,’ said Mittelman.

‘Sometimes this is a weak point for underground complexes – suffocation of those inside, but it is doubtful whether this is true for the large missile cities. The electrical infrastructure is also built on backups.’

The primary underground missile facility near Yazd is the Yazd Missile Base, a deeply buried complex identified at coordinates 31.803792°N, 54.298661°E

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Ground operations offer no easy alternative, and analysts note that inserting special forces into such deeply buried and complex tunnel systems would be high risk and difficult to scale.

Experts say each site would need to be tackled individually, across multiple heavily fortified locations.

Tal Inbar, an expert on the Iranian missile program and a senior research fellow at the Missile Defense Advocacy Alliance said: ‘The effectiveness of a ground unit in such a facility is limited, and if you really want to solve the problem, you will have to send such a unit to each of these dozens of bases, which means it will be very difficult to succeed.’

Despite weeks of sustained bombing, Iran has continued to launch missiles at Israel and its Gulf neighbours throughout the conflict. 

In the latest escalation on Friday, the Islamic Republic unleashed a ferocious attack on Gulf energy sites striking an oil refinery and desalination plant in Kuwait as well as a major gas complex in Abu Dhabi after boasting it has shot down a second American F-35 fighter jet.

The Islamic Revolutionary Guard Corps (IRGC), the feared military arm of the Iranian regime, said the aircraft was attacked over central Iran by its air defences, according to a statement carried by Mehr news agency.

Meanwhile it’s unclear how the conflict will be resolved, with Donald Trump threatening to bomb Iran ‘back to the Stone Age’ this week while simultaneously claiming the gallant US military had already won.

Trump vowed late on Thursday that the military ‘hasn’t even started destroying what’s left in Iran’.

He wrote on Truth Social: ‘Our Military, the greatest and most powerful (by far!) anywhere in the World, hasn’t even started destroying what’s left in Iran. Bridges next, then Electric Power Plants! New Regime leadership knows what has to be done, and has to be done, FAST!’

And on Wednesday, the President said Iran’s ‘ability to launch missiles and drones is dramatically curtailed, and their weapons factories and rocket launchers are being blown to pieces, very few of them left.’

The latest intelligence reports suggest a more limited effect, although Iran’s military has indeed suffered heavily.

As of Wednesday, the US had struck more than 12,300 targets inside Iran, according to US Central Command.

US Defence Secretary Pete Hegseth has pointed to a dramatic reduction in the frequency of weapons being fired by Iran.

He said on March 19 that the number of ballistic missiles and drones being launched were both down by 90 percent since the first days of the conflict.

At the same time, it is obvious Tehran has been planning for an attack like this for decades. 

The mullahs know they have several advantages over America’s military machine, not least their stranglehold over much of the global oil supply and the vulnerability of the US’s regional allies in the Gulf, who have been hit hard by Iranian strikes.

And this, combined with their lethal supply of hidden weapons, allows Tehran to set tough, probably impossible conditions even for talks to take place. 

 A cessation of hostilities and an end to the killing of Iranian officials are reasonable enough demands, but ‘reparations’ for damage caused by US bombing and a guarantee of Iranian sovereignty over the Strait of Hormuz will be too much for Washington to stomach.

Meanwhile, although the pace of Iranian strikes has slowed compared to the early days of the war, it has stabilised into a steady rhythm, suggesting that sufficient infrastructure remains operational.

Perera said: ‘The persistence of Iranian missile fire despite three weeks of intensive strikes is not resilience. It is infrastructure.’

‘IRGC did not prepare for this war by building rockets. It prepared by building railways inside mountains. The rockets are replaceable. The railways are permanent. And the granite that protects them was formed before mammals existed. 

‘The strait is 21 miles wide. The mountain is 500 metres deep. And the railway inside it is still delivering missiles to the surface,’ he added.