North Korea tests likely if they 'don't feel satisfied' -Pentagon chief

U.S. Defense Secretary Mark Esper said on Monday that North Korea's rhetoric was concerning and Pyongyang would likely carry out tests if they "don't feel satisfied," amid fears the two countries could return to the collision course they had been on before launching diplomacy.

"We have seen talk of tests. I think that they will be likely if they don't feel satisfied," Esper told reporters traveling with him from Luxembourg back to Washington. He did not provide details on what type of tests may be likely.

"I've been watching the Korean Peninsula for maybe a quarter of a century now. So I'm familiar with their tactics, with their bluster and I think we need to get serious and sit down and have discussions about a political agreement that denuclearizes the Peninsula," Esper said.