Evidence has emerged that North Korea has restarted a nuclear reactor believed to be capable of producing weapons-grade plutonium in a development called "deeply troubling," Reuters reported, citing the International Atomic Energy Agency. 

The IAEA’s report, which was released on Friday, said the reactor in question is located in the city of Yongbyon. Since last month, there have been "indications consistent with the operation" of the reactor. One key piece of evidence was the discharge of cooling water at the facility, the report said.

This picture taken on September 3, 2017 and released by North Korea's official Korean Central News Agency (KCNA) on September 4, 2017 shows North Korean leader Kim Jong-Un attending a meeting with a committee of the Workers' Party of Korea about the test of a hydrogen bomb, at an unknown location. (STR/AFP via Getty Images) (STR/AFP via Getty Images)

Leif Eric Easley, a professor of international studies at Ewha Womans University in Seoul, told the Financial Times that it seems as though the North Koreans were not intent on being discreet and could be getting ready to use Yongbyon as a bargaining chip in negotiations.

"But even if Pyongyang is considering returning to negotiations…it may lead off with a missile test rather than diplomatic engagement," he said.

The Reuters report pointed out that the country’s last nuclear test was in 2017 but the UN agency does not have access to the site after being expelled in 2009. The agency now uses commercial satellite images and other methods to monitor the facilities.

The report said there were indications of the operation of Yongbyon’s radiochemical laboratory from mid-February to early July this year.


"(North Korea’s) nuclear activities continue to be a cause for serious concern. Furthermore, the new indications of the operation of the 5-megawatt reactor and the radiochemical laboratory are deeply troubling," the IAEA said.

The Associated Press contributed to this report