north korea re-opens its plutonium-producing nuclear reactor in the hope it could expand the banned nuclear program despite offering to dismantle part of the facility under a deal

North Korea appears to have restarted its plutonium-producing reprocessing reactor, a possible sign Pyongyang is expanding its banned weapons program.

In a report dated Friday, the International Atomic Energy Agency - a UN watchdog - called the development, 'deeply troubling.'    

The 5-megawatt reactor in YongByon - North Korea's main nuclear complex - is believed to have been inactive since 2018, and its reactivation comes with nuclear talks between Pyongyang and Washington at a standstill.

The reactor produces plutonium, one of the two key ingredients used to build nuclear weapons along with highly enriched uranium. 

In 2019, North Korean leader Kim Jong Un offered to dismantle part of the Yongbyon complex at a second summit with then US president Donald Trump but not other sites, in exchange for sanctions relief.

His offer was rejected.

A cooling tower at the Yongbyon nuclear complex is demolished in 2008. North Korea appears to have restarted the operation of its main nuclear reactor there capable of producing weapons-grade plutonium

The facility had been the subject of nuclear talks between North Korean leader Kim Jong Un, and the Trump administration in 2019. Un had offered to dismantle part of the Yongbyon, but not other sites, in exchange for sanction relief. The offer was rejected

President Joe Biden's administration has said it reached out to the North Koreans to offer talks, but Pyongyang has said it has no interest in negotiating without a change in policy by the United States. 

North Korea is under multiple sets of international sanctions over its nuclear weapons and ballistic missile programs, which have seen rapid progress under Kim.

'Since early July, there have been indications, including the discharge of cooling water, consistent with the operation of the reactor,' the International Atomic Energy Agency said in its annual report.

IAEA inspectors were kicked out of North Korea in 2009, and the agency has since monitored it from outside.

The agency said it uses satellite imagery and open source information to monitor developments in North Korea´s nuclear program. 

The possible operation of the reactor follows a recent indication that Pyongyang is also using a nearby radiochemical laboratory to separate plutonium from spent fuel previously removed from the reactor. 

'The new indications of the operation of the 5MW reactor and the radiochemical laboratory are deeply troubling,' the agency said in its report.  

Satellite image from March 2 provided by Maxar Technologies shows North Korea's main atomic complex in Yongbyon. The International Atomic Energy Agency has been using such imagery to monitor the state of the country's nuclear program since being kicked out of the country in 2009 

In June, the IAEA flagged indications of possible reprocessing work at Yongbyon to separate plutonium from spent reactor fuel that could be used in nuclear weapons.

In Friday's report, the agency said the five-month duration of that apparent work, from mid-February to early July, suggested a full batch of spent fuel was handled, in contrast to the shorter time needed for waste treatment or maintenance. 

'No way to know why the reactor wasn´t operating previously - although work has been ongoing on the water reservoir over the past year to ensure sufficient water for the cooling systems,' said Jenny Town, director of the U.S.-based 38 North project, which monitors North Korea.

'The timing seems a little strange to me, given the tendency for flooding in coming weeks or months that could affect reactor operations.'

Last year 38 North said floods in August may have damaged pump houses linked to Yongbyon, highlighting how vulnerable the nuclear reactor's cooling systems are to extreme weather events.

In recent months, North Korea has warned it would expand its nuclear program if the United States doesn't withdraw its 'hostile' policy on the North, in an apparent reference to US-led sanctions and regular US-South Korean military drills. 

Kim Jong Un has vowed in recent months to expand its nuclear program if the US does not withdraw its 'hostile' policy on the north

A senior US State Department official said Washington was aware of the report and was closely coordinating with partner countries.

'This report underscores the urgent need for dialogue and diplomacy so we can achieve the complete denuclearization of the Korean Peninsula,' the official told AFP.

'We continue to seek dialogue with the DPRK so we can address this reported activity and the full range of issues related to denuclearization.'

US North Korea envoy Sung Kim last week re-iterated his willingness to meet his North Korean counterparts 'anywhere, at any time'.

North Korea is believed to be running multiple other covert uranium enrichment facilities. 

North Korea may be trying to extract plutonium to make more nuclear weapons at the complex, recent satellite photos indicated, weeks after leader Kim Jong Un vowed to expand his nuclear arsenal

According to a South Korean estimate in 2018, North Korea might already have manufactured 20-60 nuclear weapons. 

Pyongyang has stayed away from nuclear talks since the collapse of the second Trump-Kim summit in Hanoi and has rebuffed South Korean efforts to revive dialogue.

About 60 miles north of Pyongyang, Yongbyon is home to the country's first nuclear reactor, and is the only known source of plutonium for North Korea's weapons program.

Yongbyon is not believed to be North Korea's only uranium enrichment facility and closing it down would not in and of itself signal an end to the country's atomic program.

North Korea suspended nuclear and missile testing during a diplomatic process in 2018 but said it was abandoning its self-declared moratorium in January 2020.

It has subsequently carried out a series of short-range missile launches but has not conducted a nuclear test since 2017.