According to an American researcher, the Israeli airstrike on Saturday hit a building that was part of of Iran’s inactive nuclear weapons development program.

According to him and a second researcherfacilities used for the mixing solid propellants for rockets.

Estimates based on satellite images were made separately by David Albrightformer UN weapons inspector, and Decker Evelethassociate research analyst at CNA, a think tank in Washington.

The two told Reuters that the Israel hit buildings in Partchin, a huge military complex near Tehran. Israel also hit Khojir, according to Eveleth, a major missile production site also near Tehran.

Reuters reported in July that Khojir was undergoing massive expansion.

Eveleth said the Israeli strikes may have “significantly hampered Iran’s ability to mass-produce missiles.”

Israel’s military said three waves of Israeli jets struck missile factories and other sites near Tehran and western Iran early Saturday in retaliation for Tehran’s Oct. 1 missile barrage.

In posts on X, Albright said satellite images showed Israel hit a building in Partchin called Taleghan 2 which was previously used for testing during Project Amad, Iran’s defunct nuclear weapons development program.

The International Atomic Energy Agency and US intelligence agencies say Iran ended that nuclear program in 2003. Iran denies it is pursuing nuclear weapons.

Albright, head of the research group at the Institute for Science and International Security, gained access to the program’s files for a book after the files were stolen by the Mossad in 2018.

At X he said the files revealed that Iran maintained significant testing equipment at Taleghan 2.

Iran may have removed important materials before the Israeli airstrike, he said, but “even if there was no equipment inside,” the building would have “intrinsic value” for future nuclear weapons-related activities.

Albright told Reuters satellite images of Partchin showed Israel destroyed three buildings about 320 meters from Taleghan 2. Two of them contained mixed solid ballistic missile fuel.

Eveleth said an image of Partchin from Planet Labs, a commercial satellite company, showed Israel destroyed three solid ballistic missile fuel mixing buildings and a warehouse at the sprawling complex.

Planet Labs images also showed an Israeli strike destroyed two buildings at the Khojir compound where solid fuel for ballistic missiles was being mixed, he said.

The buildings were enclosed within high hills, according to the image seen by Reuters. Such structures are associated with missile production and are designed to limit the shock wave from potential explosions.

“Israel reported that it targeted buildings housing solid fuel mixers,” Eveleth said. “These industrial mixers are difficult to build. Iran has imported many in recent years, they are very expensive and will probably struggle to replace them.”

With a limited operation, he said, Israel had dealt a significant blow to Iran’s ability to mass-produce missiles and made any future Iranian missile attack against Israel difficult.

“The hits seem to be extremely accurate,” he said.

The website Axios reported Israel destroyed 12 ‘planetary mixers’ which are used to produce solid fuel for long-range ballistic missiles, citing three unnamed Israeli sources who said this seriously harms Iran’s ability to renew its missile stockpile and could deter Iran from further mass missile attacks against Israel.

Iran has the Middle East’s largest missile arsenal and has supplied missiles to Russia for use against Ukraine, and to Yemen’s Houthis and Hezbollahaccording to US officials.

Tehran and Moscow deny that Russia has received Iranian missiles