SEOUL, Aug. 30 (UPI) -- North Korea appears to have begun operating a nuclear reactor capable of producing weapons-grade plutonium after a pause of more than 2 1/2 years, according to a new report by the United Nations' International Atomic Energy Agency.
The 5-megawatt reactor at the Yongbyon Nuclear Research Facility has shown indications of use since last month, according to the IAEA report, which was submitted to the agency's board of governors on Friday.
"There were no indications of reactor operation from early December 2018 to the beginning of July 2021," the report said. "However, since early July 2021, there have been indications, including the discharge of cooling water, consistent with the operation of the reactor."
The nuclear agency has not had access to North Korea since 2009, when Pyongyang expelled its inspectors, and has used satellite imagery to monitor activity at the facility.
The report also detected operations at a steam plant that serves the radiochemical laboratory at Yongbyon from February until July, a time frame it said was "consistent with the time required to reprocess a complete core of irradiated fuel from the 5MW(e) reactor."
"The new indications of the operation of the 5MW(e) reactor and the Radiochemical Laboratory are deeply troubling," the report said. "The continuation of the DPRK's nuclear program is a clear violation of relevant U.N. Security Council resolutions and is deeply regrettable."
The Democratic People's Republic of Korea is the official name of North Korea.
In a statement released Sunday, North Korea's Foreign Ministry condemned the exercises as "the most vivid expression of the U.S. hostile policy against the DPRK."
The North will "continuously build up the strongest war deterrent in order to overpower ever-worsening military threats from the U.S.," the statement said.
Pyongyang has not conducted any nuclear or long-range missile tests since 2017, but it launched a pair of short-range ballistic missiles in March, in violation of United Nations sanctions.
A March report from a U.N. Security Council panel of experts found that North Korea has "not only continued to develop and modernize its ballistic missile program but has also increased its nuclear strike capability."
The panel assessed that the Yongbyon center is capable of producing around 7 kilograms of plutonium per year and said the country may have a stockpile of 60 kilograms of the radioactive chemical element.
The number of nuclear warheads Pyongyang possesses is uncertain. Last month, the Bulletin of the Atomic Scientists estimated that North Korea has produced enough fissile material to build between 40 and 50 nuclear weapons, but said that it may not have actually assembled that many.
Washington's efforts at nuclear negotiations with Pyongyang have been stalled since a February 2019 summit between North Korean leader Kim Jong Un and then-U.S. President Donald Trump ended without an agreement.
The Biden administration has signaled a willingness to engage diplomatically with North Korea, taking what it characterizes as a "calibrated and practical approach."
"I continue to stand ready to meet with my North Korean counterparts anywhere, at any time," Sung Kim told reporters.