Who sits where? What's on the agenda? Will they eat together? What's the security plan?

President Donald Trump and his team have a daunting to-do list to work through as they prepare for next month's expected summit with North Korean leader Kim Jong Un.

Trump's plan to meet with Kim may have come as a surprise decision, but his team hopes to leave nothing to chance when they come together in Singapore. They're gaming out policy plans, negotiating tactics, even menu items.

"We're working on the details, the actual blocking and tackling at the meeting," Secretary of State Mike Pompeo said last Sunday on CBS' "Face the Nation." ''We have been working on them for weeks."

With two unpredictable leaders, it's hard to anticipate every possibility. But White House aides are expecting hard-ball negotiating tactics — already in evidence this week as the North Koreans cast fresh doubt on the sit-down.

Leader summits on this level are a massive undertaking. Much like icebergs, only a small fraction of the work is visible above the waterline. And when the meeting involves the heads of two technically still-warring states, the list of logistical concerns expands, including sensitive items like the number and deployment of security officers. Officials on both sides are still determining the format for the meeting or meetings, whether Trump and Kim will share a meal, and the extent of any one-on-one interactions.

All of that comes as the U.S. formulates its strategies for the talks, including what the U.S. is prepared to give up and how precisely to define "denuclearization" on the Korean Peninsula — Trump's stated goal.

"I would say there are hundreds if not thousands of hours put into summit preparations," said Patrick McEachern, a public policy fellow at the Woodrow Wilson Center and a former State Department official.

Scott Mulhauser, a former chief of staff at the U.S. Embassy in Beijing, said that in the leadup to summit meetings, staffs try to anticipate the various negotiating positions their counterparts might take, adding that "if you're not gaming that out, you're not preparing adequately."

Trump is relying heavily on his top diplomat, Mike Pompeo, in preparing for the summit. Pompeo has met with Kim twice in Pyongyang, once as secretary of state and once as CIA chief, and has spent more time with the reclusive leader than any other American official. The amount of face time Pompeo has had with Kim rivals even that of most Asian leaders, apart from the Chinese.

Pompeo assembled a working group to handle negotiations with North Korea led by a retired senior CIA official with deep experience in the region. That team, based at CIA headquarters in Langley, Virginia, remains the center of the administration's North Korea expertise.

Planning for the summit started quickly after Trump announced on Twitter his plans to meet with Kim, but kicked into higher gear after John Bolton became Trump's national security adviser last month. In addition to Pompeo's two trips to Pyongyang, U.S. officials have also been coordinating with the North Koreans through what's known as the "New York channel" — North Korean diplomats posted to their country's mission to the United Nations.

A key question is the format for the meeting if the two countries are able to proceed to full-fledged nuclear negotiations, U.S. officials have said. That includes decisions about whether to keep the talks limited to the U.S. and North Korea or whether to bring other governments into the process, such as South Korea, China, Russia and Japan. Also key is what the U.S. will negotiate away.

"One thing that is unclear to us is what the U.S. is willing to negotiate in exchange for North Korea's promises on denuclearization," said Jean Lee, director of the North Korea program at the Woodrow Wilson Center and a former Associated Press bureau chief in Pyongyang. "The North Koreans are going to be armed and very ready to negotiate. The Trump administration needs to be ready as well."

One initial hurdle that Pompeo managed to clear during his second visit to Pyongyang was the venue for the summit. North Korea was adamant that Kim not be put in any kind of situation where his security could be at risk, U.S. officials said. North Korean officials pushed very hard for the meeting to be in Pyongyang, so Kim would not have to leave the country and they could have 100 percent control over access and communications, according to the officials.

When North Korea objected to Trump's preferred choice of the demilitarized zone on the border between North and South Korea, the U.S. countered with Singapore. Some White House officials also opposed the DMZ choice, believing the optics on Korean rapprochement would distract from the focus on denuclearization.

U.S. officials said they believed one reason the North Koreans agreed to Singapore was that Kim had just returned from a successful trip to China the day before Pompeo arrived for his second visit. Many analysts, including U.S. officials, believe that Kim's flight to the Chinese port of Dalian — the first trip abroad by aircraft by a North Korean leader in decades — was likely a test of the country's ability to safely transport Kim by air. Kim's previous trips to China had all been by train, as was the custom of his father.

The North formally signed off on Singapore while Pompeo was in Pyongyang. Even before Trump announced the summit site by tweet a day after Pompeo's return, White House officials who traveled with Pompeo to Pyongyang were already on the ground in Singapore to begin working out summit logistics.

Very few people have had much direct contact with the North Koreans, so there are few people for the Trump administration to check with for guidance.

Bill Richardson, the former New Mexico governor and U.N. ambassador who has negotiated with the North Koreans, had one suggestion. He said that in the meeting setting, the North Koreans will be very formal, so building a rapport between the two will be vital.

His main advice: "Try to find some private time between President Trump and Kim Jong Un."