As the summit between Washington and Pyongyang takes shape, it remains to be seen what President Donald Trump and North Korean leader Kim Jong Un will discuss next week in Singapore.

While the subject of denuclearizing the Korean peninsula is expected to take the lion’s share of the bilateral talks, one expert raised concerns that Trump may not “stay on script” when asked for other deals by the North Koreans.

“I’m sure he [President Trump] will be getting a short list of talking points, but I think the fear is that he might give away too much,” Suzanne DiMaggio, a senior fellow at nonpartisan think tank New America, said Monday during a discussion at the Stimson Center in Washington, D.C.

DiMaggio regularly holds discussions with North Korean representatives and helped facilitate the first unofficial discussions between the Trump administration and North Korean government. She offered five pieces of advice for Trump:

• Make it clear that the U.S. is ready for a different kind of relationship with North Korea.
• Tell Kim Jong Un face-to-face that the U.S. policy toward North Korea is not regime change.
• Reiterate that denuclearization on the peninsula is the end goal.
• Address the human-rights abuses in North Korea.
• After the summit, let seasoned diplomats see to day-to-day developments and broker a deal.

On the latter point, DiMaggio said that while the Trump administration is due credit for these unprecedented talks with North Korea, the president should “get out of the picture” after the summit.

“My advice would be to go to this summit, get the photo op and secure the win. To say that he has generated great chemistry with Kim Jong Un is something that no president has done,” DiMaggio said. “Then he should just get out of the picture.”

DiMaggio noted that during the summit Pyongyang could, for example, ask Trump for the withdrawal of U.S. troops from the region.

“I’m particularly worried about if Kim raises the idea of withdrawing U.S. troops from the peninsula, and suddenly president Trump says sure, we can do that. Those are the kind of things that are keeping me up at night,” DiMaggio said. “I think it’s too early to do that and it’s certainly too early to give that away as a concession. We have to do it consultation with the South Koreans.”

She noted that Trump has already mentioned he would like to do that, although it would contradict Secretary of Defense James Mattis’ recommendations.

After attending the Shangri-la Dialogue in Singapore, Mattis told reporters aboard his plane en route to Washington that there are no plans to draw down troops in South Korea.

“We’re not going anywhere,” Mattis said of the approximately 28,500 U.S. troops stationed in South Korea. “It’s not even a subject of the discussion.”