The UN nuclear watchdog's 35-nation board decided on Tuesday to close its investigation into whether Iran once had a secret nuclear weapons programme, opting to support Tehran's deal with world powers rather than dwell on its past actions.
In a symbolic victory for Iran, the International Atomic Energy Agency's (IAEA) Board of Governors passed a resolution ending its long-running inquiry but allowing inspectors to continue to police the country's nuclear programme.
"The decision by the Board of Governors today (Tuesday) will open a new chapter for cooperation between Iran and the agency," Iran's ambassador to the IAEA, Reza Najafi, told reporters after the resolution was passed by consensus unopposed.
The IAEA produced a report this month that strongly suggested Iran engaged in coordinated activities aimed at developing a nuclear bomb up until 2003, though it found no credible sign of weapons-related work beyond 2009.
Despite the finding â€” the clearest indication yet by the IAEA, after 12 years of investigation, that Iran was pursuing atomic bomb capability even though it denies that accusation â€” the international response to the report has been muted.
The United States, Russia, Britain, France, Germany and China reached a deal with Tehran in July under which sanctions weighing on Iran's economy would be lifted in exchange for restrictions on the Islamic Republic's atomic activities.
Those six powers want to press ahead with implementing the July accord, regarded as a breakthrough after years of increasing confrontation over the issue that raised fears of a wider Middle East war.
They hoped the IAEA report produced under the deal would draw a line under the long-disputed issue of so-called "possible military dimensions" to Iran's activities.
They have also highlighted, however, that even after the investigation of Iran's past is closed, the IAEA will continue to police Tehran's activities.
With companies from the six powers and other nations lining up to do business in the Islamic Republic once the sanctions are lifted, there had been little opposition to the resolution.
"It's not something one should celebrate," one Vienna-based diplomat said on condition of anonymity. "But for Iran it's a great day, undoubtedly. I could see them in the room, they were holding their breath."