How Iran might be preparing itself for a potential US strike

Satellite images analysed by Sky News' Data and Forensics team show Iran has fortified its nuclear and defence facilities, alongside conducting live drills with Russian forces amid rising tensions with the US military.

What we know about activity at Iran's nuclear facilities Iran appears to be fortifying defences at its nuclear plants and military facilities since strikes by Israel and the US in June 2025 damaged infrastructure at three key sites. Core enrichment activity remains constrained and under close international scrutiny.

The main sites affected by last year's strikes were Fordow Fuel Enrichment Plant, Natanz enrichment facility and Isfahan Nuclear Fuel Complex. They are key to Iran's core nuclear infrastructure.

The Isfahan Complex is in central Iran, 135 miles south of Tehran, near the city of Natanz. It is central to the nuclear fuel cycle, converting uranium into forms suitable for enrichment.

Isfahan includes an underground area where diplomats say much of Iran's enriched uranium has been stored. Iran's authorities have always said they are not trying to develop nuclear weapons.

Satellite images from 6 December 2025 to 24 January 2026 show structural repair and new efforts to bury tunnel entrances to the site. Satellite images show "efforts to prepare for an attack" from the US, said David Albright, founder and president of the Institute for Science and International Security (ISIS) nonprofit.

He told Sky News: "At nuclear weaponisation sites, we see cleaning up and then, in some cases, rebuilding the facilities." He added: "You have this clear preparation in anticipation for attack, trying to minimise potential weak points." The ISIS institute reported on February 9 that "backfilling the tunnel entrances would help dampen any potential airstrike and also make ground access in a special force raid to seize or destroy any highly enriched uranium that may be housed inside difficult". At the Natanz nuclear facility, a site built for uranium enrichment, satellite images appear to indicate signs of construction at the Pilot Fuel Enrichment Plant, which was damaged by both US and Israeli air strikes in June.

Just over a mile from Natanz, there is a new site, Pickaxe Mountain, also known as Kolang Gaz La. Images show the construction and hardening of tunnel shafts.

Albright told Sky News: "At Pickaxe now, we can clearly see that they've taken steps to strengthen the tunnel entrances, which are a major vulnerability of these underground facilities." Deep inside a mountain near the city of Qom, around 90 miles south of Tehran, the Fordow fuel enrichment plant was also largely destroyed by the US, said Albright, with the entrance sealed up shortly after the 2025 strikes. There has been "very little activity" there since, he said.

"From our point of view, some of these protection measures, particularly at Isfahan, indicates there's something valuable still inside," said Albright. "Whether it's recoverable or not we don't know." Other key military sites Satellite imagery also shows Tehran repairing and fortifying other complexes essential to Iran's operations.

Parchin military complex is one of Iran's most sensitive military sites. It has been covered in concrete, as shown by satellite images from 24 January.

Reports suggest that 20 years ago, Tehran conducted tests linked to nuclear bomb detonation methods at the site. Tehran has consistently rejected this.

Israel reportedly struck Parchin in October 2024. On 22 January, an analysis by the Institute for Science and International Security (ISIS) pointed to progress in the construction of a "concrete sarcophagus" around a newly built facility at Parchin.

ISIS reported in November that imagery showed "ongoing construction and the presence of what appears to resemble a long, cylindrical chamber, maybe a high-explosives containment vessel, likely measuring approximately 36 meters long and 12 meters in diameter, placed inside a building". It added that high-explosive containment vessels are critical for nuclear weapons.

It is not the only roof. Iran also built a roof over a destroyed facility at the Pilot plant to cover it and "hide activities.