WASHINGTON — President Donald Trump starkly warned North Korea to stop making nuclear threats Tuesday in the kind of bellicose rhetoric usually associated with the rulers in Pyongyang, twice declaring they will be "met with fire and fury" like the world has never seen.
The president's dramatic threat of annihilation raised fresh fears of a confrontation with North Korea, which successfully tested an intercontinental ballistic missile last month for the first time and which has vowed to defend itself with nuclear weapons if necessary.
Trump's heated rhetoric apparently caught the Pentagon by surprise and followed a new classified intelligence assessment indicating North Korea has developed a warhead design that could fit atop an ICBM.
The intelligence report hardens previous classified assessments that date back to 2013 and reflects growing confidence by the U.S. intelligence community that Pyongyang had achieved a nuclear weapons milestone after years of uncertainty.
U.S. officials caution North Korea still has not produced a nuclear warhead capable of surviving the intense heat, vibration and pressure of an ICBM's fiery re-entry into the atmosphere, but that step appears increasingly likely.
A statement from North Korea's military later Tuesday did not mention Trump's threat but warned instead that Pyongyang was "carefully examining" a plan to attack Guam, the U.S. territory in the western Pacific, with "enveloping fire" from medium and long-range missiles.
It urged the Trump administration to "immediately stop its reckless military provocation" and warned "it is a daydream for the U.S. to think that its mainland is ... invulnerable."
U.S. bombers based on Guam have flown over the Korean peninsula in recent weeks in shows of force in response to North Korean missile tests. Guam hosts thousands of U.S. service members at Andersen Air Force Base and U.S. Naval Base Guam.
Trump spoke from the clubhouse of his golf resort in Bedminster, N.J., where he is on what the White House calls a 17-day working vacation. He adopted the inflammatory language North Korean leaders have used for years to threaten the United States.
"North Korea best not make any more threats to the United States," Trump told reporters, his arms folded across his chest, immediately overshadowing a meeting he had called to discuss America's opioid epidemic. "They will be met with fire and fury like the world has never seen."
He added North Korean leader Kim Jong Un "has been very threatening beyond a normal state. And as I have said, they will be met with fire, fury and frankly power, the likes of which the world has never seen before."
For years, Pyongyang's official news service has spewed out hyperbolic threats to turn Seoul into a "sea of fire" or engulf the United States in "thermonuclear war." Those threats often are received with shrugs and treated as the stuff of parody.
But with Trump responding to North Korean bombast with his own fiery threat, experts fear he raises the risk of a miscalculation that could tempt North Korea to try to up the ante.
"To start throwing out this hyperbole about death and destruction, I don't know how that's helpful," said Carl Baker, a retired Air Force officer who was stationed in South Korea, now with the Pacific Forum CSIS in Honolulu.
Until Tuesday, the Trump administration had used traditional diplomatic channels to deal with the crisis, winning a unanimous United Nations Security Council vote to impose tough sanctions on North Korea in response to its latest ballistic missile tests.
And at a regional security conference in the Philippines on Sunday, Secretary of State Rex Tillerson offered to resume negotiations with Pyongyang if it would stop ballistic missile tests as a show of good faith.
Analysts fear Trump's comments added a dangerous new level of brinkmanship to the nuclear standoff between an untested U.S. president and a North Korean ruler who is still in his early 30s.
"My concern with Kim Jong Un is that he sees the nuclear instrument as the course of his domestic legitimacy. Ultimately that could lead to miscalculation or an accident," said Scott Snyder of the Council on Foreign Relations.
"It will be interesting to see whether the Trump comments give North Korea pause or whether they proceed with additional nuclear and missile tests to keep up their perfect record of defiance," he added.
"The temperature is getting hot enough that both sides are going to potentially search for an exit ramp. But we don't know if Kim Jong Un sees negotiations as a possible exit strategy."
The latest crisis began when North Korea tested its first two intercontinental ballistic missiles last month, with the second judged powerful enough to conceivably reach California and beyond. It crashed into the Sea of Japan, apparently on target.
A Defense Intelligence Agency report dated that same day, July 28, also rang alarms.
It assessed Pyongyang is now capable of producing so-called miniaturized nuclear warheads — about the size of an outdoor garbage can — to fit atop an ICBM, a critical step in the nation's decade long march to develop a nuclear strike force, U.S. officials said.
The report, which first was disclosed by the Washington Post, also assessed North Korea has stockpiled as many as 60 nuclear weapons, although outside analysis says the arsenal is much smaller, probably fewer than 20.
In May, a U.S. intelligence threat assessment given to Congress said Kim had been "photographed beside a nuclear warhead design and missile airframes to show that North Korea has warheads small enough to fit on a missile, examining a re-entry-vehicle nosecone after a simulated reentry" and overseeing launches that purportedly simulated use of nuclear weapons in war.
Scott W. Bray, the U.S. national intelligence manager for East Asia, said in a June speech that North Korea's goal is "developing the ability to deliver a missile-based nuclear warhead to North America" but that it still faces "several critical shortfalls."
"With sufficient time, technology and testing, North Korea can overcome design deficiencies or other malfunctions, increasing the threat these systems pose to the region and advancing Kim Jong Un's goals against the continental United States," Bray said, according to a transcript released by the Office of the Director of National Intelligence.
David Albright, a former United Nations nuclear inspector, said Pyongyang might have succeeded in building a warhead small enough to fit atop a missile, but he doubts it has mastered the technical challenges of launching it on an ICBM to carry out an attack.
North Korea is not known to have developed a re-entry vehicle, which carries the warhead atop the ICBM, that can survive the intense heat, pressure and vibration as it re-enters the atmosphere from space, he said.
Nor have North Korean tests demonstrated the ability to hit a target like a city with precision, he said.
"I'm skeptical they're there," Albright said. "They could put a warhead on it, but it's very likely it would not survive re-entry or hit its target."
In North Korea's tests of intermediate range missiles, the re-entry vehicles do not appear to have survived, said Albright, who heads a Washington proliferation research organization called the Institute for Science and International Security.
Albright also has said he is doubtful North Korea had produced 60 nuclear warheads.
"I believe that North Korea has had a design for a miniaturized nuclear warhead that would fit on a ICBM class missile for some time now," said Joseph S. Bermudez Jr., a former U.S. government expert on North Korea who now works for 38 North, a private group that focuses on the country. "We just don't know how reliable it is."
He added, "All they have demonstrated is the ability to launch a missile and have it come down with a reasonable degree of accuracy" in the sea between the Korean peninsula and Japan.
Philip Coyle, a former nuclear weapons program executive and later a senior Pentagon official, said the U.S. successfully negotiated two weapons agreements with North Korea starting in the 1990s but let them lapse and squandered the next 15 years.
"It is colossal that we have wasted so much time and given North Korea so much ability to develop its weapons," he said.
He said it is not too late to negotiate an agreement, noting Iran was successfully pulled back from becoming a nuclear arms state.
"It is still possible to pull North Korea back, and the Iran deal shows it," Coyle said.
Sen. Dianne Feinstein, a California Democrat and member of the Senate Intelligence Committee, expressed concern about what she called Trump's "bombastic comments." She called on the administration to engage Pyongyang in high-level dialogue without preconditions.
"In my view, diplomacy is the only sound path forward," she said in a statement.
Sen. John McCain, an Arizona Republican and chairman of the Senate Armed Services Committee, told a radio interview in Arizona that, "I take exception to the president's comments because you've gotta be sure you can do what you say you can do. ... That kind of rhetoric, I'm not sure how it helps."