Secret Syrian Nuclear Reactor Was Almost Finished, UN Says

A secret nuclear reactor built in Syria was nearly finished and could have been used to make material for nuclear weapons, the head of the United Nations' nuclear agency said on Monday. The reactor was built in secret during the rule of Syrian leader Bashar al-Assad, who was removed from power in December 2024. UN inspectors recently visited the site and found important new details about how far the project had gone.

The International Atomic Energy Agency, known as the IAEA, is the UN group that monitors nuclear activity around the world. IAEA inspectors visited two sites in Syria last month — one in a region called Deir Ezzor and another location that Syrian authorities pointed out to them. Their findings were reported to a meeting of the agency's board of governors in Vienna, Austria.

IAEA chief Rafael Grossi said it was clear that Syria's old government had been secretly working on nuclear projects. 'They didn't want the world to know what they were doing,' he told reporters. He said the type of reactor being built was well-suited for making fissile material, which is the key ingredient needed to build a nuclear weapon.

Grossi said the reactor 'was almost completed' and that workers are still digging it out at the Deir Ezzor site today. He also said it was possible that Syrian authorities had set off explosions at the site to destroy evidence and make it harder to investigate. The site has been closed for about 18 years.

Besides the reactor, inspectors also found a fuel fabrication plant — a place where nuclear fuel for the reactor was being made. They also discovered a storage location holding nuclear fuel, uranium scraps, and waste. In total, the IAEA found about 73 tonnes of natural uranium metal at the site.

The IAEA first flagged this location back in 2011, saying it was 'very likely' being used for a nuclear reactor. Reports at the time suggested that North Korea was helping Syria build the reactor, though that connection has not been fully confirmed. On Monday, Grossi said the agency's board would decide whether to officially close the investigation file that was opened in 2011.

In 2007, Israel carried out a secret air strike on the Deir Ezzor site, though Israel did not admit to the attack until 2018. The following year after the strike, in 2008, US officials accused Syria of trying to build a nuclear reactor and acknowledged that Israel had destroyed it. The new IAEA findings suggest the reactor was much further along than many had previously believed.

Syria's new government, which came to power after Assad was removed, has been praised by Grossi for sharing information about the previously unknown site. A proposal is expected to go before the IAEA board this week that would close the long-open investigation file. However, some experts say important questions still remain unanswered.

The Institute for Science and International Security, a US group that studies the spread of nuclear weapons, said the new IAEA report added details but did not fill in all the gaps. The group said questions remain about the full scope of Syria's nuclear program and its ties to North Korea. The IAEA says it will keep working with Syria to secure the nuclear materials and continue reporting its findings.