An Israeli satellite imaging company on Thursday released images showing what it described as “unusual” movement around the Iranian Fordo nuclear facility, a one-time uranium enrichment plant buried deep underground that was converted to a research center as part of the 2015 nuclear deal.

The photographs, which show large numbers of vehicles at the entrance to the facility and other signs of increased activity there, do not in themselves indicate any violation of the nuclear accord, known formally as the Joint Comprehensive Plan of Action, or JCPOA.

The fate of the highly contentious nuclear agreement lies in the balance, with US President Donald Trump set to decide whether or not America will remain party to it ahead of a May 12 deadline.

Get The Times of Israel's Daily Edition by email and never miss our top stories Free Sign Up

The underground site was not shuttered as part of the accord, but the types of activities allowed there were heavily curtailed.

Barring a massive, heretofore undetected effort by Iran to bring Fordo back online in violation of the JCPOA, the increased activity could likely be attributed to an attempt by the Islamic Republic to imply that it is prepared to begin enriching uranium at the site if the US pulls out of the agreement.

As part of the JCPOA, Iran was forced to limit the number of centrifuges allowed inside Fordo to 1,044, which would be kept in only one wing of the facility, and agreed that it “will not conduct any uranium enrichment or any uranium enrichment related [research and development] and will have no nuclear material at the Fordo Fuel Enrichment Plant (FFEP) for 15 years.”

The International Atomic Energy Agency, which is tasked with monitoring Fordo and Iran’s other nuclear facility under the JCPOA, last released a report on the site in late February. Under the agreement, IAEA monitors are entitled to inspect the facility regularly, “including daily” if they so choose.

“Throughout the reporting period, Iran has not conducted any uranium enrichment or related research and development (R&D) activities, and there has not been any nuclear material at the plant,” the IAEA reported on February 22.

The agency did not immediately respond to a Times of Israel request for comment on the date of its latest inspection of the site.

The pictures of the Fordo plant, which were taken on April 29, were released by ImageSat International, a satellite imagery analysis firm based out of Or Yehuda in central Israel. The company is largely run by former members of the Israeli Air Force.

One satellite photograph showed cars and buses filling the Fordo facility’s parking lot. ImageSat said it “has not detected any large presence of private vehicles nor buses” in recent months.

The firm provided a second image from July 8, 2016, in which no vehicles are visible. However, an aerial photograph from April 2, 2016, shows at least 10 cars and two buses in the facility’s parking lot.

Another image shows that a gate leading to what ImageSat refers to as “uranium enrichment tunnels” was open on April 29. Before that, the gate was last seen open on November 23, 2015. However, publicly available satellite images of the site are few and far between.

ImageSat also noted the construction of new buildings at the site, which the firm said appeared to be for research and development.

There was no indication the buildings were used for research into uranium enrichment, which is expressly forbidden under the accord. Other types of scientific research are permitted at Fordo, so long as they are approved by the IAEA.

Construction of the buildings began prior to implementation of the JCPOA in January 2016 and was completed sometime in the past year, as the structures can be seen in a Google Earth image of the site from September 2017.

The facility is buried deep underneath a mountain, apparently to offer it protection against potential Israeli or American airstrikes. It is also located just outside the city of Qom, which is considered holy to Shiite Muslims, making any attempted bombing of the site more complicated.

Prime Minister Benjamin Netanyahu discussed the Fordo facility this week, as he unveiled a stunning operation by the Mossad intelligence service, in which over 100,000 documents pertaining to Iran’s nuclear weapons program were spirited from Tehran to Israel.

“You all remember the Fordo facility? The Fordo Uranium Enrichment Facility. This was a secret underground enrichment facility that the Iranians built under a mountain. You don’t put thousands of centrifuges under a mountain to produce medical isotopes. You put them there for one reason: nuclear weapons, enrichment for nuclear weapons,” Netanyahu said.

The prime minister noted that construction of the facility took place after Iran was meant to have ended its atomic weapons program — known as Project AMAD — in 2003.

“You also will not be surprised that Iran insisted on keeping Fordo. And amazingly, the nuclear deal enabled it to do it,” he said.

[mappress mapid=”6353″]

While no official announcement has been made by the US regarding the future of the JCPOA, multiple sources told Reuters on Thursday that Trump had “all but decided” to abandon the deal and impose new sanctions against Iran.

Iranian Foreign Minister Mohammad Javad Zarif on Thursday responded to Trump’s threats to pull out of the deal with a threat of his own. “If the US continues to violate the agreement or if it withdraws altogether, we will exercise our right to respond, in a manner of our choosing,” he said in an English-language video.