Senior Israeli officials say Iran worked covertly after attacks on its nuclear sites during the Twelve Day War, to accelerate its ‘Weapon Group’ project.
Israel has said that after the destruction of three Iranian nuclear sites by the United States and Israel during the Twelve Day War last June, Iran continued clandestine efforts to restore its nuclear weapons program.
On March 3, the Israel Defense Forces (IDF) said that it “struck and destroyed the secret nuclear headquarters in Minzadehei, located partly underground in the city of Tehran. A team of nuclear scientists was operating covertly at this headquarters.”
The military added that during the June 2025 strikes, “the Iranian regime transferred some of its capabilities to secret bunkers and attempted to restore its efforts and conceal them.”
Senior Israeli security officials told Epoch Magazine in Israel that at the Minzadehei site that was struck, a team of nuclear scientists—reassembled by Iran from among those who had survived the bombing last year—was working to accelerate the country’s “Weapon Group” project. The purpose of the project is to develop the bomb’s fuzing system–the component responsible for triggering the detonation mechanism—and adapt the weapon for delivery by ballistic missile.
The officials spoke on condition of anonymity as they were not authorized to publicly discuss the details.
The Weapon Group is the body responsible for developing the nuclear detonation mechanism within Iran’s nuclear program. In the process of developing a nuclear bomb intended for mounting on a ballistic missile, the bomb’s components are developed and built separately until the weapon’s final assembly. The team of scientists operating at the site was working on the fuze.
The same sources said the Iranian leadership recovered from the blow it suffered to its nuclear sites from the United States and Israel in June 2025, and that Supreme Leader Ali Khamenei ordered an accelerated push to produce a nuclear bomb.
In 2024, Kamal Kharrazi, an adviser to Khamenei, said in an interview with Al Jazeera: “We have no decision to build a nuclear bomb but should Iran’s existence be threatened, there will be no choice but to change our military doctrine.”
In 2025, Ali Shamkhani, a former defense minister and then an adviser to Khamenei, said if he returned to the defense portfolio, he would “move toward building an atomic bomb.” Shamkhani was among the Iranian leaders killed in the U.S.–Israeli strikes on the first day of the latest military operation on Iran.
Israeli security officials say those remarks reflected growing recognition at the top of the Iranian leadership that the absence of nuclear capability was a strategic disadvantage—one that weakens the Iranian regime’s ability to deter its enemies and defend against military strikes or attempts at regime change. For that reason, achieving the ability to produce a nuclear bomb quickly became a top priority for Tehran.
By Yoni Ben Menachem and Oren Shalom
