The chief commander of the United States Air Force has downplayed Pyongyang’s claim that it has miniaturized nuclear warheads.

During a news conference at the Pentagon on Monday, U.S. Air Force Chief of Staff General Mark Welsh said he spends a lot of time worried about whether the North could ever develop the capability. 

The Air Force chief, however, stressed that he does not think the North is at the level yet.

On Wednesday, the North’s state media quoted North Korean leader Kim Jong-un as claiming the regime had succeeded in miniaturizing nuclear warheads to fit them onto a ballistic missile.