WASHINGTON (Reuters) - The United States is very concerned that North Korea might not be able to be deterred, a senior Trump administration official said on Thursday, drawing a distinction between Washington’s view of Pyongyang and its model for dealing with former Cold War foes.

The official, speaking to reporters on condition of anonymity, also said there was a grave risk that North Korea might “miscalculate” the U.S. response to its behavior and warned Pyongyang not to “under-estimate American will to protect ourselves and our allies.”

While U.S. experts are continuing to assess the North Korean nuclear test - its sixth and most powerful - the official that there was no information to contradict Pyongyang’s assertion that it detonated a hydrogen bomb.