Rubio says US expects Iran response on proposal on Friday
US Secretary of State Marco Rubio said on Friday that Washington expected to receive Iran’s response to a US proposal later in the day.
“We should get Iran response today,” Rubio told reporters during a visit to Italy.
Rubio said the United States had not yet received Tehran’s reply, adding: “I hope it’s a serious offer” and “hope that it puts us in a process of serious negotiation.”
“We will not negotiate with Hezbollah. We are focused on the Lebanese government,” Rubio said when asked about tensions involving Israel, Lebanon and Iran.
The Washington-based Institute said three other attacked sites could also be nuclear-related, but there was not enough information to be certain. In total, it said six to nine recently attacked sites were nuclear-related.
The most consequential finding is that four to seven of those sites were directly, or possibly, connected to nuclear weaponization – the process of turning nuclear material into an actual bomb.
Iran’s nuclear program has two main parts. One is producing enriched uranium, the material that can be used as fuel for civilian reactors or, at much higher levels, in a nuclear weapon. The other is weaponization: designing, testing and producing the components needed to make a working bomb.
The Institute’s report suggests the latest strikes focused heavily on the second part.
It said the recent phase of the war appeared aimed less at Iran’s already damaged enrichment infrastructure and more at degrading its ability to make the weapon itself. Some of the sites hit in this phase had not previously been publicly identified, the report said, offering new insight into what it described as the extent of Iran’s nuclear weapons-related work.
Across both phases of the war – the 12-day conflict in June 2025 and the renewed fighting from February 28 until a ceasefire on April 7/8, 2026 – the Institute said nine to 12 sites involved in developing and building nuclear weapons were targeted.
The report said Iran’s major enrichment facilities remained severely damaged from the June 2025 war. It said there was no significant new damage to facilities directly associated with uranium enrichment because they had already been destroyed, and that no reconstruction or renewed enrichment had been detected.
But the Institute said the latest strikes added another layer of damage by targeting places linked to the practical work of making a bomb.
One of the most important sites was Min-Zadayi (also Minzadehei), a previously unknown complex east of Tehran.
Israel described it as a secret nuclear compound where scientists were working on a key component of a nuclear weapons system. The Institute said later reporting suggested the site may have been involved in metallurgy – likely work connected to producing the uranium metal core of a nuclear weapon.
In simple terms, that would be one of the most sensitive stages of bomb-making: taking nuclear material and preparing it in the physical form needed for a weapon.
Satellite imagery showed three large above-ground buildings destroyed at Min-Zadayi, as well as craters near hillside and possibly partially buried structures, the report said.
Another major target was Taleghan 2, inside the Parchin military complex. The site has long been associated with Iran’s past nuclear weapons work under the Amad Plan, a program believed to have been halted in its original form in 2003 but followed by later, more concealed work.
The Institute said Iran had rebuilt and heavily fortified Taleghan 2 before it was hit in March. Satellite imagery showed earth-penetrating weapons struck the facility directly. The report said the site may have contained high-explosive containment equipment.
That is significant because high explosives are central to the design of many nuclear weapons. They are used to compress nuclear material rapidly and evenly, a crucial step in producing a nuclear explosion.
The report also mentioned strikes near the Mojdeh site, also known as Lavisan 2, and at Malek Ashtar University. Both have been linked in the report to Iran’s nuclear weapons research network.
A newly built engineering-laboratory building near Mojdeh was destroyed, while a building at Malek Ashtar was described by Israel as a research and development site used to develop components for nuclear weapons production.
Other targets included the Shahid Chamran Group complex, which the Institute connected to nuclear-related research, and a building at Imam Hussein University that Israel labeled as a physics center used for Iran’s nuclear program.
The strikes also hit two sites tied to Iran’s broader nuclear fuel cycle. The Arak heavy water production plant was destroyed more thoroughly than during the June war, the Institute said. Heavy water can be used in certain types of reactors that can produce plutonium, another possible route to a nuclear weapon.
The Ardakan Yellowcake Production Plant was also rendered inoperable. Yellowcake is an early processed form of uranium. It is not bomb material, but it is a starting point for later nuclear work, including enrichment.
Enriched uranium stockpile
Despite the damage, the report does not suggest Iran’s nuclear challenge has been eliminated.
The most important unresolved issue is Iran’s enriched uranium stockpile. The Institute said tunnel complexes at Esfahan and near Natanz were not directly attacked in this phase and are believed to hold most of Iran’s enriched uranium, including about 440 kilograms of uranium enriched to 60 percent.
That level is below weapons-grade, but far above what is typically needed for civilian nuclear power and much closer to the level needed for a bomb.
The Institute said Iran had sealed some tunnel entrances before the latest war and that much of the enriched uranium appears “bottled up” in places where movement would be easier to detect. But without international inspection, the exact status of the material remains unclear.
The report also said additional nuclear scientists were killed, including senior figures linked to SPND, the military research organization associated with Iran’s nuclear weapons-related work. The Institute drew a distinction between knowledge, which cannot be destroyed, and practical know-how, which can be much harder to replace in a secret weapons program.
The overall picture is therefore one of severe damage, but not finality as Iran may still possess a large stockpile of enriched uranium, and underground sites remain a central uncertainty.
The Institute’s assessment is that the attacks have increased both the time Iran would need to build a nuclear weapon and the chance that an attempt could fail. Its argument is not simply that buildings were destroyed, but that Iran lost facilities, equipment and people connected to the difficult final steps of making a usable weapon.
