The United Nations' nuclear watchdog, the International Atomic Energy Agency (IAEA), has concluded its long-running investigation into Syria's past secret nuclear activities. The IAEA’s 35-member board of governors, based in Vienna, unanimously approved a resolution to end the probe into Syria’s past nuclear work, which had uncovered evidence of a reactor designed to produce fissile material—material that could be used in nuclear weapons. The resolution, proposed by Egypt, Jordan, Morocco, and Saudi Arabia, marked the end of nearly two decades of scrutiny. Inside the board room, diplomats were heard applauding the decision, signaling the resolution of a long-standing international concern. The IAEA first raised concerns in June 2011, when it found Syria in violation of its nonproliferation commitments for secretly constructing a nuclear reactor in Deir el-Zour. The agency reported the issue to the U.N. Security Council and the U.N. General Assembly, prompting discussions about potential sanctions. Under the Nuclear Non-Proliferation Treaty (NPT) and Syria’s safeguards agreement with the IAEA, the country is legally required to declare all nuclear activities and allow IAEA inspectors to verify that nuclear materials are not being used for weapons. Syria had not fully answered the IAEA’s questions about the Deir el-Zour site after it was destroyed in a 2007 Israeli airstrike. Following the fall of Syrian President Bashar al-Assad in December 2024, the new government in Damascus agreed to grant IAEA inspectors access to suspected former nuclear sites. The recently adopted resolution decided to "terminate" the provisions of the 2011 resolution, officially ending the IAEA’s investigation into Syria’s non-compliance. However, the resolution emphasized that Syria remains bound by its NPT obligations and encouraged continued cooperation with the agency, including excavation work at the Deir el-Zour site. It also asked IAEA Director General Rafael Grossi to keep the board informed about the outcomes of ongoing activities in Syria. The Deir el-Zour site became public knowledge after Israel’s 2007 airstrike destroyed the facility. Syria later demolished the site and never fully answered the IAEA’s questions about it. The new resolution praised the transparency and cooperation of Syria’s current authorities and acknowledged their efforts to resolve the non-compliance issue. During a visit to Syria in August, Grossi and senior inspectors observed excavation work at the Deir el-Zour site and inspected other locations, including facilities for fuel production and storage. They also discovered a previously undeclared site where 73 tonnes of natural uranium metal—55 tonnes in the form of fuel rods—were found. All of this material is now under IAEA monitoring.