US bombs unlikely to reach underground Iran nuclear site: Report

New Iranian atomic facility near Natanz may be too deep underground to be destroyed by air raids, AP analysis says.

Satellite view showing construction work
This satellite photo from Planet Labs PBC shows construction on a new underground facility at Iran's Natanz nuclear site near Natanz, Iran on April 14 [Planet Labs PBC via AP]

Near a peak of the Zagros Mountains in central Iran, workers are building a nuclear facility so deep in the earth that it is likely beyond the range of a last-ditch United States weapon designed to destroy such sites, according to experts and satellite imagery analysed by The Associated Press news agency.

The photos and videos from Planet Labs PBC show Iran has been digging tunnels in the mountain near the Natanz nuclear site, which has come under repeated sabotage attacks amid Tehran’s standoff with the West over its atomic programme.

With the country now producing uranium close to weapons-grade levels after the collapse of its nuclear deal with world powers, the installation complicates the West’s efforts to halt Tehran from potentially developing an atomic bomb, which Iran denies seeking.

The report on Monday comes amid a spike in Iran-US tensions and stalled diplomacy between the two countries.

Completion of such a facility “would be a nightmare scenario that risks igniting a new escalatory spiral,” warned Kelsey Davenport, the director of nonproliferation policy at the Washington-based Arms Control Association.

“Given how close Iran is to a bomb, it has very little room to ratchet up its programme without tripping US and Israeli red lines. So at this point, any further escalation increases the risk of conflict,” Davenport told AP.


This month marked five years since former President Donald Trump unilaterally withdrew from a multilateral nuclear deal that saw Iran scale back its nuclear programme in exchange for a lifting of international sanctions against its economy.

The administration of US President Joe Biden has continued to impose and enforce a strict sanctions regime against Iran and its oil and petrochemicals industries. Meanwhile, Tehran has been advancing its nuclear programme.

Biden, who was vice president to Barack Obama when the 2015 agreement was signed, had promised to revive the pact, but numerous rounds of indirect talks over the past two years have failed to restore it.

Since the demise of the nuclear accord, Iran has said it is enriching uranium up to 60 percent – up from the 3.67 percent limit it observed under the deal. Inspectors also recently discovered the country had produced uranium particles that were 83.7 percent pure, just a short step from reaching the 90 percent threshold of weapons-grade uranium.

As of February, international inspectors estimated Iran’s stockpile was more than 10 times what it was under the Obama-era deal, with enough enriched uranium to allow Tehran to make “several” nuclear bombs, according to the head of the International Atomic Energy Agency (IAEA).

The US and Israel – which is widely believed to have its own covert nuclear arsenal – have said they won’t allow Iran to build a nuclear weapon. “We believe diplomacy is the best way to achieve that goal, but the president has also been clear that we have not removed any option from the table,” the White House said in a statement to the AP.

Iran’s mission to the United Nations, in response to questions from the AP regarding the construction, said that “Iran’s peaceful nuclear activities are transparent and under the International Atomic Energy Agency safeguards.”

Iran says the new construction will replace an above-ground centrifuge manufacturing centre at Natanz struck by an explosion and fire in July 2020. Tehran labelled the attack at that time as “nuclear terrorism” and blamed it on Israel.

Tehran has not acknowledged any other plans for the facility, though it would have to declare the site to the IAEA if authorities planned to introduce uranium into it. The Vienna-based IAEA did not respond to questions about the new underground facility.

The new project is being constructed next to Natanz, about 225km (140 miles) south of Tehran. Natanz has been a point of international concern since its existence became known two decades ago.

Protected by anti-aircraft batteries, fencing and Iran’s paramilitary Revolutionary Guard, the facility sprawls across 2.7sq km (1sq mile) in the country’s arid central plateau.

Satellite photos taken in April by Planet Labs PBC and analysed by the AP show Iran burrowing into the Kuh-e Kolang Gaz La, or “Pickaxe Mountain”, which is just beyond Natanz’s southern fencing.

A different set of images analysed by the James Martin Center for Nonproliferation Studies reveals that four entrances have been dug into the mountainside, two to the east and another two to the west. Each is 6m (20 ft) wide and 8m (26 ft) tall.

The scale of the work can be measured in large dirt mounds, two to the west and one to the east. Based on the size of the spoil piles and other satellite data, experts at the centre told AP that Iran is likely building a facility at a depth of between 80m (260 ft) and 100m (328 ft). The centre’s analysis, which it provided exclusively to AP, is the first to estimate the tunnel system’s depth based on satellite imagery.

“So the depth of the facility is a concern because it would be much harder for us. It would be much harder to destroy using conventional weapons, such as… a typical bunker buster bomb,” said Steven De La Fuente, a research associate at the centre who led the analysis of the tunnel work.

The new Natanz facility is likely to be even deeper underground than Iran’s Fordow facility, another enrichment site that was exposed in 2009 by the US and others. That facility sparked fears in the West that Iran was hardening its programme from air attacks

Such underground facilities led the US to create the GBU-57 bomb, which can plow through at least 60m (200 ft) of earth before detonating, according to the US military.

US officials reportedly have discussed using two such bombs in succession to ensure a site is destroyed, according to AP. It is not clear that such a one-two punch would damage a facility as deep as the one at Natanz.

Source: Al Jazeera, The Associated Press