The Pentagon expressed concern on Tuesday about a UN report indicating possible reprocessing of nuclear fuel for bombs by North Korea.
Top officials said such activity could raise tensions between Washington and Pyongyang.
Rear Admiral Michael Studeman, head of intelligence for the US Indo-Pacific command, said North Korean activity highlighted this week by the International Atomic Energy Agency (IAEA) could be intended to get the attention of the Biden administration and act as a bargaining chip to press for sanctions relief, Reuters reports.
The Biden administration is currently reviewing US-North Korea policy.
“We have our eye on this. And it is deeply concerning where North Korea wants to go,” Studeman told a virtual security conference.
In a statement to the IAEA Board of Governors on Monday, the United Nations body’s director general, Rafael Mariano Grossi, referred to increased activity at North Korea’s Yongbyong and Kangson nuclear facilities.
He said there had been recent indications of a steam plant operating that could serve as a radiochemical laboratory. North Korea has used its radiochemical lab at Yongbyon to reprocess plutonium from a reactor there for nuclear bombs.
Grossi called North Korea’s continued nuclear activity a clear violation of UN sanctions and “deeply regrettable”.
Referring to Grossi’s statement, Studeman said: “The IAEA board of governors issued a notice that there had been evidence of the Koreans reprocessing perhaps nuclear fuel.”
The administration of President Joe Biden, which took office in January, is conducting a full review of North Korea policy following former president Donald Trump’s unprecedented engagement with North Korean leader Kim Jong Un, which failed to persuade Pyongyang to give up its nuclear weapons.
Biden’s Secretary of State Antony Blinken has said the approach to North Korea could involve more sanctions or unspecified diplomatic incentives.