US intelligence chief calls NK potentially 'existential' threat to US

"North Korea is an increasingly grave national security threat to the United States because of its growing missile and nuclear capabilities combined with the aggressive approach of its leader, Kim Jong-un. Kim is attempting to prove he has the capability to strike the US mainland with a nuclear weapon," Coats said.

"It's clear that we have assessed this as a very significant, potentially existential threat to the United States that has to be addressed," he said. "We have dedicated a very significant amount of our intelligence resources to the issue of North Korea."

The intelligence community will continue to dedicate resources to the problem, he said.

"It requires some of our most talented professionals to warn our leaders of impending North Korean actions and of the long-term implications of their strategic weapons programs," he said.

Coats also said China can play a significant role in dealing with the North.

CIA Director Mike Pompeo gave a more positive assessment of the Chinese efforts to rein in the North, saying the country has "made efforts in a way that they have not made before."

But he said China can and should do more.

"The intelligence suggests we're going to need more to shake free this terribly challenging problem. And that they could do more. And they have the capacity to do more as well," he said. (Yonhap)