In this image taken from video footage run Wednesday, March 28, 2018, by China's CCTV via AP Video, North Korean leader Kim Jong Un, left, and Chinese President Xi Jinping shake hands in Beijing. (AP/AP)

The White House on Wednesday declared itself “cautiously optimistic” that the planned summit with North Korean leader Kim Jong Un will take place sometime in May, even as key details such as where Kim will meet with President Trump, and the parameters of their talks, remain undetermined.

“We feel like things are moving in the right direction,” press secretary Sarah Huckabee Sanders said.

The Trump administration was initially thrown off balance when China announced late Tuesday that it had held its own summit with Kim this week, according to U.S. officials and people familiar with internal diplomatic discussions.

Amid debates about whether the Chinese move was good or bad for U.S. aims, administration officials ultimately decided to declare it a positive result of its “maximum pressure” campaign against North Korea.

But Beijing’s failure to officially inform the United States until after its talks with Kim were over and he had departed for Pyongyang aboard his armored train was another indication of the uncertainties that still surround Trump’s North Korea gambit.

The president said on Twitter early Wednesday that he had received a message from Chinese President Xi Jinping late Tuesday that the meeting with Kim “went very well and that KIM looks forward to his meeting with me.”

A State Department spokesman said that the “personal message” from Xi was conveyed as part of a briefing the White House received from the Chinese government after the visit.

It remained unclear whether the administration has received a direct confirmation from North Korea about the proposed Trump-Kim summit. Kim’s invitation to meet was conveyed to the White House by South Korea early this month, and Trump quickly accepted.

As far as the administration is concerned, State Department spokesman Justin Higgins said, the messages conveyed by Seoul and Beijing are enough confirmation to begin planning.

“North Korean leader Kim Jong Un has said he is committed to denuclearization, pledged to refrain from any further nuclear or missile tests, and understands routine joint military exercises between the Republic of Korea [South Korea] and the United States will continue,” Higgins said. “Kim also expressed his desire to meet with President Trump as soon as possible.

“In light of this, President Trump has accepted Kim Jong Un’s offer to meet in person.”

Trump’s national security staff, with his newly designated national security adviser and secretary of state not yet in place, has held a series of discussions on the upcoming summit, but senior officials said even the most basic questions have not been answered.

No decision has been made among a number of options for the location of the meeting, including the Peace House in the demilitarized zone between North and South Korea, or countries such as Sweden that maintain diplomatic relations with both North Korea and the United States.

While some experts have suggested Beijing, a senior administration official said that was likely to be unacceptable to the White House because the location is “a major espionage risk, for starters.” Official U.S. visitors to China assume that their conversations, movements and private meetings are monitored, and that all of their bags are thoroughly searched.

Another question is whether there will be what the official called “senior-level engagement” between the two governments before the summit.

“I can’t rule it out. The president and [Kim] are not going to hash out” details of their meeting “over the phone,” said the official, who spoke on the condition of anonymity about closed-door planning.

Such preliminary, agenda-
setting meetings are common before summits, and are often conducted at the foreign-minister level. Confirmation hearings for CIA Director Mike Pompeo, Trump’s nominee for secretary of state, are unlikely to be held until well into April.

John Bolton, Trump’s designee to take H.R. McMaster’s place as White House national security adviser, has not yet started work in the job, which McMaster is due to vacate April 9.

Both Pompeo and Bolton have been outspoken hawks on North Korea, with Pompeo suggesting last summer that regime change there would be a welcome development and Bolton advocating military strikes.

Bolton, who served as the head of arms-control policy at the State Department during the George W. Bush administration, wrote in a 2007 book that he made it his personal mission to “shatter” the nuclear agreement in force with North Korea at the time, on grounds that Pyongyang had cheated and could never be trusted.

“The Democratic People’s Republic of Korea (DPRK) will never give up nuclear weapons voluntarily,” he wrote. “It often promises to do so . . . [and] will even more readily bargain over that promise, especially in exchange for items of tangible economic and political value.”

The idea that a rogue state could be persuaded to give up nuclear weapons was an illusion, Bolton wrote. “The DPRK will gladly ‘engage’ with us, accept our concessions, and then violate its own commitments. . . . Ironically, North Korea’s policies have often been more sensible than our own, where the hope of the High Minded seems always to triumph over contrary experience.”

Trump seemed to take the opposite tack early Wednesday. “For years and through many administrations, everyone said that peace and the denuclearization of the Korean Peninsula was not even a small possibility,” he said in another tweet. “Now there is a good chance that Kim Jong Un will do what is right for his people and for humanity. Look forward to our meeting!”

Bolton has acknowledged that he “has his own views and has been outspoken” in his writing and on television as a commentator for Fox News, the senior official said. “He has also said that as national security adviser he will put those views aside and make himself an arbiter of options” placed before the president by his senior national security advisers.

Defense Secretary Jim Mattis, who has advocated diplomacy with North Korea, told reporters Tuesday that he had “no reservations, no concerns at all” over Bolton. “Last time I checked, he’s an American, and I can work with an American,” Mattis said.

Kim’s China visit was believed to be his first trip outside the country since he took over North Korea’s government six years ago. Replete with an official dinner and laudatory official statements, it marked a shift in Beijing’s noticeably chilly attitude toward Pyongyang over the past year, including support for increased sanctions and criticism of North Korea’s accelerated nuclear weapons program.

Xi’s decision to meet with Kim was seen by some experts as an effort to take control of the situation as North Korea’s main economic and diplomatic partner, as well as a reaction to Trump’s lack of consultation before agreeing to meet Kim, and to last week’s announcement of new U.S. trade penalties against China.

“Panicked is too strong a word, but they seemed concerned or very wary ever since Thursday,” when Trump signed the memorandum authorizing $60 billion in new intellectual property tariffs against China, said Michael Pillsbury, a China scholar at the Hudson Institute and a defense adviser on East Asia during the George H.W. Bush administration. “They had been assured by various friends that these things wouldn’t happen.”

The “Trump people,” Pillsbury said, “were upset they didn’t get advance consultation from Xi.” His advice to them, he said, was to consider it “a big breakthrough for you. . . . It’s China stepping up to the plate.”

Another reason “the Chinese jumped,” said Robert Carlin, a former U.S. intelligence officer and State Department adviser on North Korea negotiations, “was because they had the feeling Kim was deliberately cutting them out­ . . . with his moves toward South Korea and the United States.”

Carlin also suggested that Kim wanted to meet with Xi because “he needs to have his flanks covered. He needs to know that the Chinese are not going to do something to sell him out, which they did once before,” he said, citing an earlier episode in the long, convoluted history of negotiations over the future of the Korean Peninsula.

John Hudson contributed to this report.