Washington (CNN) Administration officials are scrambling to turn President Donald Trump's surprise decision to meet North Korean leader Kim Jong Un into a reality, preparing for an unprecedented, high stakes summit with little time, an understaffed State Department and a mercurial President who may not stick to his script when the time comes.

The White House will convene a meeting Tuesday to discuss preparations, an administration official said. Secretary of State Rex Tillerson cut short a trip to Africa to "get his hands around what's happening," the official said. In the meantime, Tillerson and other senior officials reached out to allies worldwide and lawmakers on Capitol Hill to brief them on the decision.

White House spokeswoman Sarah Sanders said the administration is preparing on a "number of levels," an "interagency process" that she declined to describe further.

High stakes, North Korean silence

Foreign capitals are moving quickly as well, with the South Korean and Japanese foreign ministers announcing plans to meet with Tillerson in Washington on Friday for more in-depth consultations.

Even as the world reacts, North Korea has maintained silence, not responding to Trump's announcement last week. US Cabinet officials are moving to calm expectations and urge patience.

The stakes are high if this summit goes awry, analysts say, particularly if North Korea responds by resuming missile or nuclear testing. Indeed, many analysts stressed that Trump himself will be a wild card, both during the summit itself and afterward, should things go wrong.

"The greatest risk to negotiations is not North Korea," said DJ Peterson, president of Longview Global Advisors, a geopolitics advisory group for businesses and political organizations. "It's Washington, it's the White House. You see people like Tillerson already trying to minimize any potential for missteps, miscues, miscommunications."

"There are significant risks for failure here," said Peterson.

That risk is compounded by the fact that the circumstances are topsy-turvy. Summit meetings between national leaders usually take place only at the very end of negotiations, after lower-level bureaucrats have hammered out every detail of an agreement and scripted every pause and handshake in their public appearance.

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But the announcement Thursday surprised officials at the White House, Pentagon and State Department, not to mention US lawmakers and foreign leaders. Senior administration officials had to dissuade Trump from meeting Kim in April and convince him to wait until May, after the leaders of North and South Korea hold their own summit.

On Monday, Sanders said the administration fully expects the meeting to take place. "The offer was made and we accepted," she said, noting that Pyongyang made several promises ahead of the meeting.

Trump touted those pledges, all conveyed through South Korean officials, on Twitter over the weekend. The North Korean leader reportedly expressed a commitment to denuclearization and Trump noted that Kim also "has promised" not to conduct missile tests "through our meetings. I believe they will honor that commitment!"

"We hope they will stick to those promises, and if so, the meeting will go on as planned," Sanders said.

Short-staffed

But with the administration understaffed and lacking regional experts, it's a concern that Trump and his officials can be fully prepared in 10 weeks for this meeting, analysts say. Trump is not known to have a nuanced understanding of the Korean Peninsula or to be an avid consumer of the daily intelligence briefing.

The administration is also lacking an ambassador to South Korea as well as a special envoy for North Korea, and there are a slew of questions to address.

Those questions range from the basic where, when and how to more nuanced issues, including how the US should approach the talks, whether Washington should accept anything short of North Korean denuclearization and whether to involve the fates of three Americans held hostage by Pyongyang.

Returning to Washington from Africa, Tillerson told reporters Monday that he was ready to prepare Trump for the challenge ahead.

"I have a lot of confidence in my ability to create the conditions for successful negotiations between two very disparate parties," Tillerson said. "But I'm not the only guy working on this. Others are working on this as well."

The top US diplomat indicated the US wouldn't be inclined to have the talks take place in China. "I think we're going to be wanting to find a nice neutral site where both parties will feel confident with the site for this meeting between President Trump and Kim Jong Un," Tillerson said, "and so my view is we ought to find someplace that's neutral."

Tillerson also said he would work on the challenge of preparing Trump with others within the administration.

"We have an obligation to prepare the President for that meeting," Tillerson said. "I think there is some groundwork we can do ahead of that that will help with that preparation. That's what we're talking about again with other agencies, and I had a fair amount of telephone time calling others to talk about this within our own government."

Critics have warned that North Korea might simply use the talks to stall for time to complete advances on its nuclear and ballistic missile programs.

All this heightens the dangers posed by Trump's impulsive decision, which already gives the North Koreans a huge win in the validation and recognition of a face-to-face meeting with a sitting US president.

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Kim Jong Un is "in the driver's seat at the moment," Wendy Sherman, the former chief US nuclear negotiator with Iran, told CNN's Christiane Amanpour.

"He has been able to get the President of the United States -- the most powerful leader in the world -- to sit in the same room as him as if he is an equal," Sherman said. "So he's already achieved a major objective from his perspective."

Sherman, who served as special adviser to President Bill Clinton on North Korea, traveled to North Korea with then-Secretary of State Madeleine Albright in 2000. Sherman said that while she did not believe Kim is "in any rush to denuclearize," she was glad that the US is entering into talks, even if it just starts with "a meeting.

"Talk is certainly better than war."

Nonetheless, she cautioned that if approached incorrectly, a diplomatic effort ending in failure could become a "pretense" for war.

The "greatest risk," she said, is "that the President and his team give this an effort, but because they don't get every single thing that they want, that they say it's hopeless, and really create the prerequisite for war."

"There are lots of choices that are going to have to be made, and if the President feels that they all have to go the way that the United States wants them to go, we probably won't get to an agreement -- and we probably will find ourselves at war."

Adding to the risk is the fact that there's been little public preparation for the development in the three countries most concerned -- the US, North Korea and South Korea -- and that could put pressure on the leaders if things go badly.

Trump is widely unpopular in South Korea, according to analysts based there, and vilified in North Korea, just as he has spent months demonizing Pyongyang and threatening it with "fire and fury."

Peterson, of Longview Global Advisors, notes that while the North Korean leader is "going to get a meeting with the President, if that meeting doesn't go well, what is he going to show his people or other people in his administration for failure? What if they revert to missile or nuclear development? Then how will Trump react? How do we ignore it?"

Indeed, Tillerson, who was in Africa when Trump called to inform him of his decision to meet Kim, was quickly working to manage expectations as he made plans to return early to Washington.

"With respect to the ongoing discussions about a potential meeting between President Trump and Kim Jong Un, as you know it's a very recent development," Tillerson cautioned reporters during a stop in Nigeria on Monday.

'We'll see what happens'

"Several steps will be necessary to agree on location, agree on the scope of those discussions. It's very early stages," Tillerson said. "We've not heard anything directly back from North Korea, although we expect to hear something directly from them. ... I would say just remain patient and we'll see what happens."

Asked about possible meeting locations, Tillerson added that "nothing's been agreed, and I don't want to start floating ideas out through the media. I think it's going to be very important that those kind of conversations are held quietly through the two parties."

An administration official said it wasn't unusual that the North Koreans hadn't responded yet and that Tillerson has no plans, as yet, to meet with the North Korean foreign minister -- a typical step in the run-up to any summit meeting.

"This is just the beginning of the process. We're not there yet," the administration official said, speaking on condition of anonymity to discuss the situation. "The secretary has not spoken to the North Koreans. I don't think it's that unusual" that we haven't heard from the North Koreans yet.

"This is the beginning of that process. We're planning those meetings. The South Koreans are clearly heavily involved."