Senior aides to President Trump repeatedly warned him not to deliver a personal attack on North Korea's leader at the United Nations this week, saying insulting the young despot in such a prominent venue could irreparably escalate tensions and shut off any chance for negotiations to defuse the nuclear crisis.
Trump's derisive description of Kim Jong Un as "Rocket Man" on "a suicide mission" and his threat to "totally destroy" North Korea were not in a speech draft that several senior officials reviewed and vetted Monday, the day before Trump gave his first address to the U.N. General Assembly, two U.S. officials said.
Some of Trump's top aides, including national security advisor H.R. McMaster, had argued for months against making the attacks on North Korea's leader personal, warning it could backfire.
But Trump, who relishes belittling his rivals and enemies with crude nicknames, felt compelled to make a dramatic splash in the global forum.
Some advisors now worry that the escalating war of words has pushed the impasse with North Korea into a new and dangerous phase that threatens to derail the months-long effort to squeeze Pyongyang's economy through sanctions to force Kim to the negotiating table.
A detailed CIA psychological profile of Kim, who is in his early 30s and took power in late 2011, assesses that Kim has a massive ego and reacts harshly and sometimes lethally to insults and perceived slights.
It also says that the dynastic leader — Kim is the grandson of the communist country's founder, Kim Il Sung, and son of its next leader, Kim Jong Il — views himself as inseparable from the North Korean state.
As predicted, Kim took Trump's jibes personally and especially chafed at the fact that Trump mocked him in front of 200 presidents, prime ministers, monarchs and diplomats at the U.N.
Kim volleyed insults back at Trump in an unprecedented personal statement Thursday, calling Trump "a mentally deranged U.S. dotard" and a "gangster" who had to be tamed "with fire."
Kim's foreign minister, Ri Yong Ho, threatened to respond with "the most powerful detonation," a hydrogen bomb test in the Pacific Ocean, according to South Korea's Yonhap News Agency.
Trump lobbed another broadside Friday, tweeting that Kim "is obviously a madman" who starves and kills his own people and "will be tested like never before."
The clash may undermine Trump's other efforts on the sidelines of the General Assembly meetings.
He spent much of Thursday meeting with Japanese Prime Minister Shinzo Abe and South Korean President Moon Jae-in in an effort to carve out new ways to pressure Kim to freeze or roll back his nuclear program.
On Thursday, Trump announced new U.S. sanctions against other countries, foreign businesses and individuals that do business with North Korea, a move likely to chiefly affect China, Pyongyang's largest trading partner.
John Park, a specialist on Northeast Asia at Harvard's Kennedy School, said the tit-for-tat insults have created a "new reality" and probably have shut off any chance of starting talks to curb North Korea's fast-growing nuclear arms program.
"If the belief centers around sanctions being the last hope to averting war and getting North Korea back to the negotiating table, it's too late," Park said.
Since taking office, Kim has pushed the nuclear and missile programs far faster than U.S. experts had expected, sharply accelerating the pace of development and tests. Kim has conducted four of the country's six nuclear tests.
U.S. officials now believe that North Korea has fully one-third of its economy invested in its nuclear and missile programs.
Trump and his senior aides say Kim has used foreign assistance, including trading subsidies from China, to offset such massive spending. They believe the latest U.S. sanctions, on top of the U.N. sanctions, will help choke off some of that income.
In recent months, Pyongyang has tested its first two intercontinental ballistic missiles, conducted an underground test of what it claimed was a powerful hydrogen bomb, and fired midrange ballistic missiles over northern Japan.
U.S. experts assess that North Korea is six to eight months away from building a small nuclear warhead robust enough to survive the intense heat and vibrations of an intercontinental ballistic missile crossing the Pacific and reaching the continental United States.
Given Kim's record of putting political rivals and dissenters to death, including members of his own family, his public statement blasting Trump makes it highly unlikely that other North Korean officials would participate in talks about ending the country's nuclear program, Park said.
"There is no one on the North Korean side who is going to entertain or pursue discussion about a diplomatic off-ramp, because that individual would be contradicting the leader, which is lethal," Park said.
Trump has returned to rhetoric he'd used during the campaign, when he called Kim a "madman playing around with nukes" and a "total nut job."
But Trump also praised Kim at the time, saying during a Fox News interview last year that Kim's "gotta have something going for him, because he kept control, which is amazing for a young person to do."
The president has been fixated on the threat from Pyongyang since taking office.
Trump "rarely lets me escape the Oval Office without a question about North Korea," CIA Director Mike Pompeo said in July at a national security forum in Aspen, Colo. "It is at the front of his mind."
But Trump also has expressed frustration at the failure of previous administrations to block North Korea's advances in ballistic missile and nuclear technology despite negotiations, sanctions, export controls, sabotage and other efforts.
President Clinton, and then President George W. Bush, engaged in two major diplomatic initiatives to convince North Korea to abandon its nuclear weapons efforts in return for aid. Both initiatives ultimately collapsed. President Obama reportedly tried cyber-sabotage.
Obama warned Trump before he took office that North Korea would be his most pressing international concern, and the new president was alarmed to learn how close Kim was to developing an intercontinental ballistic missile that could deliver a nuclear warhead to U.S. soil.
Despite all of that, Trump rarely derided Kim by name after he entered the White House.
In May, he said he'd be "honored" to meet Kim under the right circumstances.
In August, after U.S. intelligence analysts became convinced Pyongyang had miniaturized a nuclear warhead, Trump said the country would face "fire and fury" if it made more threats against the United States. But he stopped short of hurling personal insults.
Matthew Kroenig, a political scientist at Georgetown University and expert on nuclear deterrence, said Trump's threat this week to "totally destroy" North Korea comes out of the U.S. playbook for preventing a nuclear attack.
"The point is to deter a North Korean attack, and the art of deterrence hasn't changed," he said in a phone interview Friday. "It is to convince your adversary that the benefit of committing an attack would be outweighed by the costs."
"That's what Trump was making clear — it is not in Kim Jong Un's interest to attack the U.S.," Kroenig said.
4:15 p.m.: This article was updated with additional details about past efforts to halt North Korea's nuclear program and Trump's public statements on the country.