A satellite image from April 8 shows the new roadblocks at the Isfahan tunnel complex that houses some of Iran's stockpile of highly enriched uranium. Photo / Pleiades, Airbus DS
Iran is building roadblocks at a key nuclear complex amid threats of a US or Israeli ground operation to seize its stockpile of highly enriched uranium.
According to satellite imagery, the regime has blocked Isfahan’s three tunnel entrances with earthen berms, fences and piles of rubble.
Construction of the defensive measures began on or after March 18, the Washington-based Institute for Science and International Security reported. They would delay any raid and expose troops to Iranian missile fire, analysts told The Telegraph.
At least half of Tehran’s stockpile of 400kg of highly enriched uranium (HEU) – the key ingredient for a nuclear weapon – is thought to be held at Isfahan, one of three main complexes alongside Fordow and Natanz.
About 200kg would provide enough to build five nuclear weapons.
US President Donald Trump has suggested US forces could storm the nuclear sites and the Iran war would not end without the regime handing over its “nuclear dust”. Iran’s rulers show no sign of agreeing to that.
On Thursday, Israel’s Prime Minister Benjamin Netanyahu warned of a military operation to seize the HEU in the absence of a deal. He said in a televised address: “We still have goals to complete. The enriched material that still remains will leave Iran ... either by agreement or through a renewal of the fighting.”
Any operation to take the uranium by force would rank among one of the most challenging endeavours in modern warfare. Troops would need to fly to the site, establish a perimeter and dig for hours or days to gain access to the underground facility.
Sarah Burkhard, a senior research associate at the Institute for Science and International Security, told The Telegraph the roadblocks constructed in recent weeks would be straightforward to remove but would “add time and complexity” to a ground operation.
During the 12-day war in June last year, US B-2 bombers dropped bunker-busting munitions on Fordow, which is buried 80m deep inside a mountain. These probably destroyed centrifuges and rendered any supplies of HEU almost impossible to recover.
However, the Iranian regime may have moved material to Isfahan in the days before that war broke out. Using satellite imagery, the institute observed trucks delivering 18 blue canisters to the site on June 9.
The entrances to Iran’s largest nuclear research complex have since been filled with dirt. But the facility itself was not bombed as heavily as Fordow during Operation Midnight Hammer, meaning it may be possible to enter and remove any stocks of HEU.
Should a raid take place, Iran would probably target US or Israeli troops for as long as they were forced to remain above ground.
In the Airbus satellite imagery, a 2m-wide earthen berm and another constructed from unidentified material can be seen obstructing the southernmost tunnel entrance. Similar roadblocks cover the middle and northern tunnels.
Tehran has constructed new chicane barriers near a pre-existing checkpoint at the middle tunnel, whose main entrance area has now been entirely fenced off.
Earlier this week, Trump suggested the US would “work with” Iran to remove the HEU from its nuclear sites. But with talks set to begin on Saturday in Islamabad, Pakistan, the US President’s chief ambition for a deal now appears to be the full reopening of the Strait of Hormuz.
Netanyahu, on the other hand, has made removing Iran’s nuclear threat a key part of Israel’s military operation.
The roadblocks at Isfahan cut both ways, Burkhard said. They “increase the detection time with respect to the US retrieving the uranium”, but they would also slow any Iranian effort to remove it once more.
A ground operation would require heavy equipment to move the earth, and planes to remove the HEU, which would need to be lifted using cranes.
Burkhard said: “It would be an extraordinary venture to try something like this. But if they don’t, they have left the Iranian regime in possession of significant amounts of HEU.”
Washington will press for a deal to secure the removal of the uranium. “That would be much better,” said Burkhard, but it would take longer. Tehran may not be willing to hand over stockpiles that the US and Israeli military operation failed to secure.
If such a deal was not reached, the US could carry out further airstrikes. “We still see additional vulnerabilities” at Isfahan, Burkhard said, “even if it’s a granite mountain”.
There is a ventilation structure halfway up the mountain that presents an attractive target. Roads and utilities could also be pulverised.
She said: “We think maybe the US just hasn’t made up its mind. It thinks it might be able to get it, and remove it, more easily than destroying the mountain.”
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