"Handful of shots came across from the north; we think those were accidental," he said on ABC's "This Week."

"South Koreans did return fire. There was no loss of life on either side," he added.

The border incident came a day after North Korean state media said Kim Jong Un had made his first public appearance after a nearly three-week unexplained absence from public view.

Pompeo declined to comment on what the US knew about the North Korean leader's absence, or whether it was linked to a rumored health issue.

"We have seen the same images from yesterday that the world saw. It looks like Chairman Kim is alive and well," he said.

"Our mission remains the same, to convince the North Koreans to give up their nuclear weapons and create a brighter future for the North Korean people."