DUBAI- Iran has begun construction on a site at its underground nuclear facility at Fordo amid tensions with the U.S. over its atomic program, satellite photos obtained Friday by The Associated Press show.
Iran has not publicly acknowledged any new construction at Fordo, whose discovery by the West in 2009 came in an earlier round of brinkmanship before world powers struck the 2015 nuclear deal with Tehran.
While the purpose of the building remains unclear, any work at Fordo likely will trigger new concern in the waning days of the Trump administration before the inauguration of President-elect Joe Biden. Already, Iran is building at its Natanz nuclear facility after a mysterious explosion in July there that Tehran described as a sabotage attack.
“Any changes at this site will be carefully watched as a sign of where Iran’s nuclear program is headed,” said Jeffrey Lewis, an expert at the James Martin Center for Nonproliferation Studies at the Middlebury Institute of International Studies who studies Iran.
Iran’s mission to the United Nations did not immediately respond to a request for comment. The International Atomic Energy Agency, whose inspectors are in Iran as part of the nuclear deal, declined to comment. The IAEA as of yet has not publicly disclosed if Iran informed it of any construction at Fordo.
Construction on the Fordo site began in late September. Satellite images obtained from Maxar Technologies by the AP show the construction taking place at a northwest corner of the site, near the holy Shiite city of Qom some 90 kilometers (55 miles) southwest of Tehran.
A Dec. 11 satellite photo shows what appears to be a dug foundation for a building with dozens of pillars. Such pillars can be used in construction to support buildings in earthquake zones.
The construction site sits northwest of Fordo’s underground facility, built deep inside a mountain to protect it from potential airstrikes. The site is near other support and research-and-development buildings at Fordo.
Among those buildings is Iran’s National Vacuum Technology Center. Vacuum technology is a crucial component of Iran’s uranium-gas centrifuges, which enrich uranium.

A Twitter account called Observer IL earlier this week published an image of Fordo showing the construction, citing it as coming from South Korea’s Korea Aerospace Research Institute. (AP)