White House Weighs Response to North Korea’s Threats

WASHINGTON — The war of words between President Trump and Kim Jong-un, North Korea’s leader, raised concerns on Friday that it could escalate into a new and more volatile phase as the White House weighed its next steps in response to a threat by Pyongyang to conduct the world’s first atmospheric nuclear test in 37 years.

Mr. Trump derided Mr. Kim as a “madman” on Friday, hours after the North Korean called him a “mentally deranged U.S. dotard,” the sort of name-calling exchange most presidents have avoided. North Korea’s accompanying warning that it might test a nuclear bomb over the Pacific Ocean added fresh urgency to an administration debate over options for a pre-emptive strike if preparations for a launch are detected.

Mr. Trump’s long-distance confrontation with “Rocket Man,” as he earlier dubbed Mr. Kim, defied diplomatic convention and took the penchant for reality-show insults that he perfected on the campaign trail to the international arena — only with potential real-world consequences.

The president seemed to be gambling that the same style that put his domestic opponents on the defensive could work on the diplomatic front as well. But foreign policy veterans said the president was playing a dangerous game that at the very least complicates his own efforts to find a diplomatic resolution to the dispute over North Korea’s nuclear and missile programs.

“Personal insults make compromise more difficult,” said Kori Schake, a former national security aide to President George W. Bush now at Stanford University’s Hoover Institution. “Taunting foreign leaders isn’t a diplomatic tactic with a very good track record. And with a problem like North Korea, which has a slim margin for error and a high likelihood of misunderstanding due to North Korea’s international isolation, President Trump indulging in it is incredibly reckless.”

“When does rhetorical bombast turn into a real bomb?” Senator Benjamin Cardin of Maryland, the top Democrat on the Senate Foreign Relations Committee, said in an essay for Foreign Policy magazine. “The president’s inflammatory and irresponsible threat does not keep America or our Asian allies safe.’’

Other presidents have responded viscerally to North Korean leaders but not so publicly. Mr. Bush once told senators that Mr. Kim’s father and predecessor, Kim Jong Il, was a “pygmy” who acted like “a spoiled child at the dinner table.” But he did that in private. President Barack Obama made a point of ignoring Mr. Kim and his son.

Advisers in recent weeks have presented Mr. Trump with several pre-emption options that included cyberattacks against military or dual-use facilities, according to senior officials. Defense Secretary Jim Mattis noted that the United States had not attempted to destroy the unarmed missiles that have been tested so far, because they were not on track to hit American territory, or allies like Japan.

So far, the president has declined to explicitly lay out a red line that, if crossed, would provoke some sort of action. One senior official said that acting to prevent an atmospheric test, which would risk radiation spreading in the winds toward populated areas, could well result in a very different decision.

Such an operation would be highly risky even if it would be far more surgical than Mr. Trump’s threat this week to “totally destroy North Korea” if forced to defend the United States or its allies. Should the United States find that North Korea was loading a nuclear warhead onto an intercontinental ballistic missile, the choices would be limited, according to officials who have participated over the years in the Pentagon’s secret war games designed to anticipate various forms of a crisis on the Korean Peninsula.

For the moment, despite his bellicose language, Mr. Trump has chosen the path of economic pressure, signing a new order on Thursday intended to cut North Korea off from the international banking system with measures that, in some ways, went significantly beyond previous efforts to punish outlier nations like Iran. The White House hopes that further isolating North Korea will eventually force Mr. Kim to come to the negotiating table.

Conservatives who bristled at what they considered Mr. Obama’s weak approach offered few complaints about the president’s taunting escalation, arguing that Mr. Kim was a bully and the best way to stand up to a bully was to match him, rhetorical blow for rhetorical blow. Some urged Mr. Trump to even go beyond that, given that North Korea now has a significant nuclear arsenal with missiles that could even strike the United States.

“The question is, do you wait for one of those? Or, two?” Representative Duncan Hunter, a California Republican, said in a radio interview Thursday. “Do you preemptively strike them? And that’s what the president has to wrestle with. I would preemptively strike them. You could call it declaring war, call it whatever you want.”

John Hannah, who served as national security adviser to former Vice President Dick Cheney, said it was hard to imagine any previous president “getting into the rhetorical muck with the likes of” Mr. Kim. But he noted that all of those predecessors “failed miserably to resolve the North Korean nuclear threat,” their measured tones doing nothing to stop a dictator from developing a devastating arsenal.

“Is it a high risk strategy?” Mr. Hannah, now senior counselor at the Foundation for Defense of Democracies, said of Mr. Trump’s approach. “For sure. Is it worth trying, in light of the historical record of dismal U.S. failure to stop the North Korean program? Perhaps.”

That question was part of the discussion at the United Nations General Assembly on Friday as world leaders debated the wisdom of Mr. Trump vs. Mr. Kim.

Australia, a close American ally, said the fault lies with North Korea. “The security of millions of people is at risk as a result of North Korea’s refusal to abide by international laws and norms,” Julie Bishop, the country’s foreign minister, told the world body.

But Cuba, the longtime American antagonist, blamed Mr. Trump for raising the temperature. “We reject the threat to totally destroy the Democratic People’s Republic of Korea, home to 25 million human beings,” said its foreign minister, Eduardo Rodríguez Parrilla. “War is not an option in the Korean Peninsula.”

Hitting an unarmed missile on the launching pad — or on a mobile missile launcher — would risk starting a conflict that the North could quickly escalate, potentially with a conventional attack on Seoul, the capital of South Korea. But hitting a nuclear-armed missile could trigger exactly the nuclear detonation that the United States would be trying to prevent, depending on any safety mechanisms that the North has built into its weapons to keep them from accidentally detonating if they suffered a sharp shock.

Intercepting a warhead using missile defenses runs other dangers, White House officials have been told. If the American antimissile systems missed — against a single warhead, which should be the simplest target — it would undercut confidence in an infrastructure the United States has spent $300 billion to build over the past four decades.

If a hit succeeded, it could still spread nuclear material below — less of an issue over the water, but a serious problem if the interception occurred over land.

In recent days, administration officials have sought to emphasize that they do believe there are viable military options despite deep doubts by many national security veterans — if for no other reason that it carries no deterrent value if North Korea concludes that the United States would never try.

“There are a lot of military options that can be done,” Nikki R. Haley, the American ambassador to the United Nations, told reporters on Thursday. “And so the president is not going to spell out specifically what he’s going to do, when he’s going to do it, or where he’s going to do it. But there are many options that he’s discussed with his national security team that, should North Korea do anything irresponsible or reckless, that he has to choose from.”