JOINT BASE PEARL HARBOR-HICKAM, Hawaii — North Korea’s threat to detonate a hydrogen bomb above the Pacific Ocean is being treated as credible based on the regime’s past actions, U.S. officials here said.

That’s because in the past, North Korea has worked to manage global reactions to its nuclear tests and missile launches by announcing and socializing them publicly first, thus reducing the likelihood of any military reaction, they said.

“I would fully expect if he‘s telling us he’ll do it, he’s going to,” the officials said, who briefed reporters traveling with Chairman of the Joint Chiefs Gen. Joseph Dunford on the condition of anonymity.

The officials also provided a tour of the Hawaii base’s ability to detect launches and then relay responses to partners Japan and China on a missile’s potential trajectory. The last several months here have seen a near constant pace of launches and tests by North Korea, which has generated calls for both military options and an increased attempt to deliver a diplomatic solution.

For the regional military officials here, a diplomatic solution is the far preferred option. Even a limited and successful military campaign against North Korea could kill hundreds of thousands of Seoul residents, the Congressional Research Service estimated in a report released this week and provided to the Military Times.

The officials said even in a hypothetical, successful scenario, the risk was high that the U.S. would likely either be blamed for the deaths — either because of a perception the U.S. provoked North Korea or that it did not do enough to end Pyongyang’s nuclear program before conflict erupted.

Dunford, who has repeatedly emphasized that the military’s role is to help press a diplomatic option, said an above-ground hydrogen bomb test would be “particularly provocative.”

Dunford said any above ground test by North Korean leader Kim Jong-un would generate a very strong international response, and that they are taking this latest threat seriously.

“I have a tendency from a planning perspective to take their rhetoric seriously and make sure we are prepared to deal with it,” Dunford said. “We‘re listening carefully to what he is saying.”