North Korea has also struggled to negotiate with Mr. Trump. After a failed effort in Hanoi, Vietnam, in February to get Mr. Trump to lift sweeping American sanctions against North Korea, Mr. Kim fired his negotiating team.
But Mr. Kim has one big advantage. In the absence of careful groundwork by American diplomats, North Korea never had to agree to freeze its nuclear and missile production before entering into talks. That means Mr. Kim has added to his arsenal over the last year, making it ever more difficult for Mr. Trump to achieve his stated goal of ridding North Korea of nuclear weapons. And in any case, the country’s 30 to 60 nuclear warheads give it considerable leverage.
That may explain why the Iranians are threatening to resume production, too.
“The Iranians didn’t then and don’t now have nuclear weapons,” said William J. Burns, a deputy secretary of state in the Obama administration with a 33-year career in the foreign service, who began back-channel talks with Iran in 2013. “The North Koreans have dozens, and they’re expanding their capacity to make more.”
Mr. Burns acknowledged that relying solely on pressure from sanctions to rein in Mr. Kim did not work in the Obama years, and said Mr. Trump was right to engage diplomatically with the North Korean leader. But he said the lack of structured diplomacy meant North Korea was no closer to embracing denuclearization now than it was at the end of the Obama administration.
To draft the equivalent of the Iran nuclear deal, Mr. Burns said, “that’d be pretty serious, but you don’t do that just through summitry.”
Now that an unlikely affinity between Mr. Trump and Mr. Kim seems to be hitting its limits, each is waiting for the other to get nervous and make a concession. “With Washington and Pyongyang, they each think the ball is in the other’s court,” said Joseph Yun, the former special representative for North Korea. “I don’t think there will be movement soon.”
Mr. Bolton and Mr. Pompeo argue that if the United States continues to take a “maximum pressure” approach to North Korea through unrelenting sanctions, it will force Mr. Kim to yield to Mr. Trump’s demands.