ABOARD A MILITARY AIRCRAFT — Defense Secretary James Mattis issued a stern warning to North Korea Wednesday after news reports indicated the regime may now have the capability to miniaturize a warhead atop of a missile that could target the U.S. or its allies.

“The [Democratic People’s Republic of Korea] should cease any consideration of actions that would lead to the end of its regime and the destruction of its people,” he said in a statement provided to reporters traveling with him to the West Coast.

“The DPRK regime’s actions will continue to be grossly overmatched by ours and would lose any arms race or conflict it initiates,” he said.

President Trump brought focus to the U.S. military’s options to denuclearize North Korea after telling reporters on Tuesday, “They will be met with fire and fury like the world has never seen.”

North Korea in response said it was “carefully examining” a plan to strike the U.S. territory of Guam, where there are two U.S. military bases.

Asked by Breitbart News whether anyone in Guam should be worried, Mattis responded simply: “No.”

Despite the exchange of bellicose language between the U.S. and North Korea, Mattis emphasized that the administration’s strategy on North Korea is diplomatically-led, noting last week’s unanimously-passed United Nations Security Council resolution sanctioning Pyongyang.

“All the skeptics said we’d never pull it off, and it was pulled out. You know, it was unanimous,” he told reporters.

“What we’re doing is a diplomatically-led effort and it’s succeeding in drawing the international community together and speaking with one voice. You just saw it. That’s where we’re at,” he said.

“Do I have military options? Of course I do, that’s my responsibility to have those, and we work very close together with allies to ensure that this is not a unilateral DOD thing — this is multilateral,” he said.

“What we’re trying to do here is leave it loud and clear [in] the diplomatic arena: It’s North Korea’s choice if they want a much better future … or do they want a much worse future? Of course there is a military option. We want to use diplomacy. That’s where we are right now, and that’s where we hope to remain.”

North Korea has conducted at least five nuclear weapons tests since 2006 in violation of international law and has significantly sped up its testing of ballistic missiles, conducting 14 this year.

Most alarming were its last two tests, which officials concluded were tests of intercontinental ballistic missiles that could potentially reach the U.S. mainland.

Mattis said North Korea’s actions were alarming to the “entire world” and that he is asked about them every time he meets with a foreign leader.

“It comes up from Brussels to Singapore,” he said.

Mattis is scheduled to visit a submarine base in Seattle, Washington, on Wednesday — the first stop of a three-day trip to the West Coast focused on ties between the Pentagon and the technology industry.

Nuclear-missile armed submarines comprise one of the three legs of U.S. missile defense known as the nuclear triad, which also consists of nuclear-armed bombers and ground-based systems.

Mattis told reporters the visit to the submarine base was “long-scheduled” and not in response to recent North Korean developments.

Asked about President Trump’s January 27 order for Mattis to review and modernize the nation’s nuclear posture, Mattis said he did not want to get into specifics but that “there are already a number of things underway.”

While in Seattle, Mattis will also visit the Amazon headquarters, one of the “Big Five” leaders in technology. From there, he will head to Silicon Valley in California where he will visit the Pentagon’s Defense Innovation Unit Experimental (DIUx), an initiative started under his predecessor that aims to foster ties between the Defense Department and the tech industry. He will also visit Google headquarters.