But a meeting between Trump and Kim, these experts said, could open the door to ratifying North Korea's nuclear status or scaling back the United States' joint military exercises with South Korea. That could sunder US alliances with Japan and South Korea and play to the benefit of China, which has long advocated direct dialogue between Washington and Pyongyang. South Korean F-15K fighters drop bombs during training in August. Credit:South Korean Defence Ministry "What the North Koreans are angling for is to bring the danger and tension to a crescendo, and then to pivot to a peace proposal," said Daniel Russel, who served until March as the assistant secretary of state for East Asian affairs. "All of this is focused on pressuring the US to enter direct talks with Kim on his terms. That is the big trap." Previous presidents avoided that trap, Russel said, even if Bill Clinton briefly contemplated meeting Kim's father, Kim Jong-il. But Trump brings a dealmaker's swagger to the North Korea issue that his predecessors did not. He has in the past expressed a willingness to sit across a table from the wilful young scion of North Korea's ruling family. "I would speak to him," Trump said during the presidential campaign. "I would have no problem speaking to him." In April, he said: "If it would be appropriate for me to meet with him, I would absolutely; I would be honoured to do it."

While the Pentagon has drawn up options for a military strike on the North, officials concede it would be all but impossible, given the retaliation it would provoke and the calamitous casualties that would result. Stephen Bannon, Trump's former chief strategist, reflected that internal consensus when he told The American Prospect: "There's no military solution. Forget it." US President Donald Trump meets with his South Korean counterpart Moon Jae-in June. Credit:New York Times That leaves diplomacy, which US Secretary of State Rex Tillerson and other officials have made clear is still the administration's preferred course. If North Korea curbs its behaviour, Tillerson said recently, there is a "pathway to sometime in the early future having some dialogue". Hours after Trump ruled out talks on Twitter, Defence Secretary Jim Mattis contradicted him. "We're never out of diplomatic solutions," he told reporters. In Geneva, Robert Wood, the US ambassador to the Conference on Disarmament, said the United States remained open to dialogue. "We do not seek to be a threat to the Kim Jong-un regime," he said. Jaw-jaw better than war-war: US Defence Secretary James Mattis. Credit:Bloomberg

Trying to explain Trump's tweet, Wood, who was once the State Department's acting spokesman, said: "What the President is saying is that he doesn't see talking as solving this problem and part of the reason is that the North is not interested in dialogue." Indeed, Trump's sudden hostility to talks appeared to be less a reversal of his previous statements than an expression of frustration with Kim's continued belligerence. Days after Trump praised him for his newfound restraint, Kim lobbed a missile over Japan. A medium-range ballistic missile is launched from the Hawaiian island of Kauai in August. Credit:Missile Defense Agency via NYT For now, a Trump-Kim summit remains a far-fetched notion. Even if North Korea was interested in speaking to the US, its string of belligerent actions – not to mention the June death of Otto Warmbier, the Ohio college student held for nearly 18 months in Pyongyang – would make a meeting politically untenable for Trump. In his tweet, the President declared, "The US has been talking to North Korea, and paying them extortion money, for 25 years."

A video broadcast by North Korean television last month shows Kim Jong-un receiving a military briefing in Pyongyang. Credit:AP While Trump's precise meaning was unclear, he seemed to be referring to the promises of fuel oil, nuclear-power reactors, humanitarian aid and the lifting of sanctions that accompanied previous diplomatic negotiations. Trump, experts said, is correct that talks with North Korea – whether conducted by Democratic or Republican administrations – have been costly and unproductive. And with the North Koreans now capable, by some estimates, of producing an atomic bomb every sixth or seventh week, the cost of reaching any new agreement would be even higher. Then secretary of state John Kerry with Daniel Russel, right, in Kuala Lumpur in 2015. Russel warns that North Korea is trying to trap the Trump administration. Credit:New York Times "We're long past the point where we can fob them off with a few light-water reactors," said Michael Auslin, a research fellow at Stanford University's Hoover Institution, who argued in an essay in Politico Magazine this week that Trump should shun negotiations in favour of a policy of explicitly deterring and containing a nuclear North Korea.

Other experts said it was not diplomacy itself that was problematic – particularly if the United States negotiated, along with its allies and China – but that Trump, acting alone, could be an unpredictable negotiator. "Trump is not the first president to think he can make a deal with these guys," said Auslin. "Bill Clinton thought he was the great negotiator. His aides thought if they could get him in a room with Kim Jong-il, they could seal a deal. There's clearly a sense, because of the capriciousness of Trump and The Art of the Deal, that he could do the same." Trump's tweet could be interpreted as a negotiating tactic. But experts said he was not helping his case with his wildly divergent statements about Kim. Last Tuesday, at a rally in Phoenix, Trump said: "I respect the fact that I believe he is starting to respect us. I respect that fact very much." Further complicating the administration's approach is its weak diplomatic bench. It still has not named an assistant secretary for East Asian affairs and no ambassador is in Seoul, although the White House is close to nominating Victor Cha, a veteran of the George W. Bush administration and well-regarded North Korea expert at Georgetown University. Some experts said they took comfort from the fact that in any summit meeting, the North Koreans would never allow the Americans to determine either the setting or the terms of the negotiation. For a dealmaker and showman like Trump, that would probably be unacceptable.

"I suspect that in the end, the President might fall back on his event-planning background," said Michael Green, who served as a top Asia adviser to Bush. "This is not a Miss Universe pageant or a pro wrestling match, so that might stop Trump in his tracks." New York Times