Secretary of State Rex Tillerson, in a surprise stop in Guam on Wednesday, said he does not believe there is "any imminent threat" of a nuclear attack from North Korea and defended President Trump's "fire and fury" warning to Pyongyang as blunt talk for a country that does not seem to understand diplomatic language.

“Americans should sleep well at night,” he said as he flew from Malaysia to Washington, stopping in Guam to refuel.

Tillerson's brief stop in Guam was particularly noteworthy since North Korea, in its latest threats, warned that it is considering a missile strike on the U.S.-administered territory where the U.S. maintains military forces, among them the sprawling Andersen Air Force Base and Naval Base Guam.

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The island's positioning in the Pacific is considered a key strategic point for U.S. military planning and presence. At least 6,000 U.S. troops are stationed there.

Although the North Korean army warned Tuesday it was studying a plan to create an “enveloping fire” in areas around Guam, Tillerson said Americans should “have no concerns about this particular rhetoric of the last few days.”

His remarks come one day after Trump warned of "fire and fury" against North Korea if it continues to threaten the U.S. and its allies with nuclear attack.

Tillerson said the president aimed to send a clear message to North Korea "to avoid any miscalculation on their part."

He said Trump's remarks sent a "strong message to North Korea" in response to louder and louder rhetoric from North Korean leader Kim Jong Un.

Trump, he said, was speaking to North Korea "in language that Kim Jong Un will understand because he doesn't seem to understand diplomatic language."

He said the U.S. president "just wanted to be clear to North Korea that the U.S. (has the) unquestionable ability to defend itself, will defend itself and its allies."

Even as Tillerson spoke, Trump kept up his barrage of blunt talk, tweeting that his first order as president was "to renovate and modernize our nuclear arsenal. It is now far stronger and more powerful than ever before...."

Seven minutes later, Trump added: "...Hopefully we will never have to use this power, but there will never be a time that we are not the most powerful nation in the world!"

At the same time, the president also retweeted Fox & Friends mentions about Trump’s fiery rhetoric. One said “Trump vows U.S. ‘power’ will meet North Korean threat.” Another included a video clip of Trump vowing to respond to North Korean threats with “fire and fury.”

Tillerson told reporters aboard his plane there was never any talk about rerouting from Guam after the North Korean threat of an attack on the island, which is home to 163,000 people.

The secretary, in downplaying any imminent threat, said there were some positive diplomatic moves this week, particularly a U.N. Security Council resolution imposing stiff new sanctions on Pyongyang. The secretary noted the resolution passed with the support of China and Russia, which both have relations with North Korea.

Tillerson said “the pressure is starting to show” and explains why North Korea’s rhetoric is becoming louder and more threatening.

Tillerson added North Korea still has a way out in the form of negotiations, under the right conditions.

In Washington, the Pentagon released a statement by Defense Secretary Jim Mattis saying North Korea "must choose to stop isolating itself and stand down its pursuit of nuclear weapons."

"While our State Department is making every effort to resolve this global threat through diplomatic means, it must be noted that the combined allied militaries now possess the most precise, rehearsed and robust defensive and offensive capabilities on Earth," he said. "The (North Korea) regime’s actions will continue to be grossly overmatched by ours and would lose any arms race or conflict it initiates."