US intelligence agencies believe that North Korea has increased its production of fuel for nuclear weapons at multiple secret sites in recent months—and that North Korean leader Kim Jong Un may try to hide those facilities as he seeks more concessions in nuclear talks with the Trump administration, US officials told NBC News.

In addition, as per NBC News workers who have access to undisclosed data, Pyongyang later plans to attempt to hide from the US the existence of the facilities where that production is carried out.

“There’s no evidence that they [North Korea] are decreasing stockpiles, or that they have stopped their production,” said one US official briefed on the latest intelligence. “There is absolutely unequivocal evidence that they are trying to deceive the US.”