The intelligence authorities of South Korea and the United States are closely monitoring North Korea for signs the reclusive regime appears to have halted operations of a nuclear reactor in its Yongbyon nuclear complex, Seoul's defense ministry said Thursday.

The Dong-A Ilbo earlier reported the allies' intelligence authorities have detected signs indicating the 5-megawatt reactor temporarily stopped operations late last month, and South Korean and US officials believe the move could be related to reprocessing spent fuel rods to extract weapons-grade plutonium.

"South Korean and US intelligence authorities are closely monitoring related movements," Jeon Ha-kyou, the ministry's spokesperson, told a regular briefing when asked about the report.

The reactor in the complex, north of Pyongyang, has shown signs of being in operation since July 2021. In April, 38 North, a US website dedicated to analyzing North Korea, said North Korea appeared to be expanding and refurbishing the complex in Yongbyon, citing commercial satellite imagery.

Last week, North Korea stipulated its policy of strengthening its nuclear force in the constitution during a key parliamentary meeting.

At the meeting, North Korean leader Kim Jong-un touted the move as a "powerful political lever" to strengthen its defense capabilities, while calling the ongoing trilateral security cooperation between South Korea, the United States and Japan as the "worst actual threat." (Yonhap)