LONDON: Between June 13 and 24 last year, Israel and the US launched a series of attacks designed to cripple Iran’s nuclear program.

The target lists included the Natanz and Fordow enrichment plants, the Isfahan Nuclear Technology Center, an under-construction heavy-water reactor at Arak and dozens of other sites, including centrifuge-production facilities, laboratories and research centers. Israel’s Operation Rising Lion began on June 13, while the US struck Fordow, Natanz and Isfahan as part of Operation Midnight Hammer on June 21-22.

Days later, US President Donald Trump celebrated a mission that involved a guided-missile submarine and more than 125 aircraft, including B-2 stealth bombers, fighter aircraft and dozens of air-refuelling tankers.

“Monumental damage was done to all nuclear sites in Iran,” he said, adding: “Obliteration is an accurate term.”

But one site was conspicuous by its absence from the target lists.

Now, however, the nuclear facility known as Pickaxe Mountain may finally be in America’s crosshairs.

Pickaxe Mountain — Kuh-e Kolang Gaz La in Farsi — lies just south of the Natanz complex that was badly damaged last year.

New satellite imagery appears to confirm earlier reports of intensified activity at the site, with Iran putting in place measures that analysts believe could be designed to protect its tunnel entrances against attack.

“After Operation Midnight Hammer last June, Iran doubled down on construction at the Pickaxe facility,” Joseph Rodgers, deputy director of the Project on Nuclear Issues at the Center for Strategic and International Studies, told Arab News.

“Construction this year is higher than at any point in the site’s history.”

CSIS analysis published this month found more road activity at Pickaxe Mountain in 2026 than at any point since monitoring of the site began, including hardened portal access, reinforced entrances and work on the internal road network.

About a year ago, satellite analysis commissioned by The Washington Post revealed activity at the “mysterious underground site” that appeared to suggest Tehran had not entirely ceased work associated with its nuclear program.

International nuclear inspectors have never visited the facility, and its purpose remains unclear.

When work began on the site in 2020, Iran said it was intended to house a plant for building centrifuges needed for uranium enrichment. But fears have since grown that the facility could be used to store sensitive nuclear material or equipment.

“Mossad claims that Iran moved uranium centrifuges into Pickaxe Mountain last fall,” Rodgers said.

“Given this information, there is circumstantial evidence that Iran may be considering expanded activities at Pickaxe Mountain.

“This could include enrichment or additional nuclear research facilities, such as the metallurgy facilities that the US destroyed at Isfahan.”

CSIS cautions, however, that satellite imagery alone cannot confirm Israeli claims that centrifuges were moved into the complex or establish whether the underground facility is capable of enrichment.

One reason Pickaxe may have escaped attack last year is its depth.

Analysts estimate that parts of the complex are buried 80 to 100 meters beneath a granite mountain — potentially deeper than Fordow and beyond the effective reach of even the most powerful conventional earth-penetrating bombs in the US arsenal.

According to Behnam Ben Taleblu, senior director of the Iran program at the Foundation for Defence of Democracies, “the window to strike Pickaxe Mountain, according to some, has already expired, because the regime has dug an underground nuclear facility several times deeper than at Fordow.”

Speaking on Fox TV on Thursday, he added: “On the flipside, Washington can do what it’s traditionally been able to do with sites that are underground, hardened and fortified, and that’s to bury their entrances, and raise the political cost to the Islamic Republic of being able to dig out.”

Either way, the site has been on Washington’s radar for months, and Trump has repeatedly threatened to attack it.

In a TV interview on July 13, he said: “We have eyes on it and Pickaxe Mountain is a possible target for a nice big fat shot right in the front door.”

A week later, during a White House meeting with Lebanese President Joseph Aoun, Trump said Iran “may have” moved centrifuges into the deep underground facility.

“That’s where the action is,” he said, adding that the US could hit the site “pretty soon, and very heavily.”

On July 21, media in the US and Israel reported that Israeli intelligence had told Washington that Iran had moved thousands of centrifuges into tunnels deep inside the mountain.

Asked in a July 28 Fox News interview about reports that Israeli Prime Minister Benjamin Netanyahu had personally drawn his attention to the intelligence, Trump said: “I don’t need Bibi to tell me that.”

“Bibi’s telling me that because he wants me to stay involved.

“I know exactly what’s going on at Pickaxe. It’s not a big problem. We took out their nuclear sites, and we’ll have to take out Pickaxe if we don’t make a deal.”

The issue has returned to prominence just before Iranian leaders are due in New York for the UN General Assembly.

It also coincides with new analysis of recent imagery from Pickaxe Mountain.

The Institute for Science and International Security said satellite images taken on Sept. 11 showed that Iran had added a series of earthen piles across roads leading to the western tunnel entrances in late July and early August.

“These roadblocks are likely intended as defensive measures to prevent rapid ingress and egress to and from the tunnel portals,” the institute said.

Trump has also returned publicly to the site.

Speaking at a Republican midterm convention in Dallas on Sept. 9, he said: “We notice there’s a little activity at Pickaxe. I would advise Iran not to get cute because we will have to hit them very hard.”

His remarks came the same day CSIS published its analysis of multiple satellite images collected since 2020.

Together, the think tank said, the images revealed more road activity at Pickaxe Mountain in 2026 than at any other point in the site’s history.

There had been “a clear surge in construction activity in 2026” involving the raising and hardening of portal access points, paving of internal roads, reinforcement around entrances and the removal of excavation spoil.

The International Atomic Energy Agency has sought information about and access to the complex, but the site has yet to be inspected.

In an American television interview in September 2025, Iranian President Masoud Pezeshkian, asked about satellite imagery showing activity at the facility, dismissed the images as inconclusive and said the IAEA “can come and inspect on the ground” to establish its purpose.

But CSIS has noted the tension between Tehran’s calls for transparency and restrictions on inspectors.

The think tank has identified at least three possible explanations for what is being built inside Pickaxe Mountain.

Iran could be constructing the centrifuge-assembly facility it announced in 2020.

It could also be developing a uranium-enrichment facility capable of processing its existing stockpile of highly enriched uranium.

Alternatively, nuclear-related research previously conducted at sites damaged in US and Israeli attacks could be moved underground.

What is clear is that America’s military options for seriously damaging the facility may be limited.

“Pickaxe is buried at an estimated 80 to 100 meters deep into a granite mountain,” Rodgers told Arab News.

“This likely means that the facility is beyond the reach of the US’s most sophisticated bunker-buster bombs, such as the GBU-57 Massive Ordnance Penetrator.”

The GBU-57, which can be carried by the B-2 stealth bomber, is the largest conventional bunker-busting weapon in the US arsenal.

Fourteen of the 30,000-pound weapons were used during Operation Midnight Hammer last year — their first operational use.

Fordow, although also buried deep underground, had vulnerabilities that could be exploited during the attack.

Pickaxe presents a different challenge.

“The Pickaxe complex is quite distinct from a facility like Isfahan, which contained infrastructure above ground that was easily targeted with Tomahawk cruise missiles,” Rodgers said.

CSIS analysis indicates that Iran continued construction at Pickaxe Mountain immediately after Operation Midnight Hammer.

Between June and September 2025, Iran completed a security perimeter around the facility, reinforced several tunnel entrances and accelerated excavation work.

The design of the complex may also complicate any future attack.

CSIS said the tunnel entrances appear to have U-shaped approaches, which could prevent missiles from traveling directly along the tunnel corridors and reduce the ability of blast waves to penetrate deep into the mountain.

That could make Trump’s confidence that the US could unleash a “nice big fat shot right in the front door” harder to translate into military reality.

For Rodgers, the implications extend beyond Pickaxe Mountain itself.

“Tehran’s nuclear ambitions cannot simply be bombed away,” he told Arab News.

“Pickaxe Mountain is one of several underground facilities in Iran, and Iran will continue to drive its nuclear program underground.”

He added: “Unless the US is willing to commit to boots on the ground, the only lasting solution to this challenge is a diplomatic settlement.”