Two American delegations, one in Singapore and one in North Korea, are attempting to work out a meeting between the two leaders. Mr. Trump canceled the meeting in a letter to Mr. Kim on Thursday but has been working to reconstitute it ever since, posting Twitter messages that say he is confident the North Korean economy will prosper if an accord is reached.

The delegation in Singapore is discussing the logistics of a meeting, to be held June 12 or afterward. The other, led by Sung Kim, an American diplomat with long North Korea experience, is meeting senior officials of the North Korean Foreign Ministry at the Demilitarized Zone to work on the wording of what kind of communiqué might be issued by the two leaders. But the White House and State Department have said nothing about the details of those discussions.

In an interview, Dr. Hecker said he was making the Stanford study public to advance discussion of a complicated topic that will be at the heart of Mr. Trump’s encounter with Mr. Kim in Singapore, if that meeting happens. So far, the denuclearization agenda has been a mix of bold claims by the administration about what it will demand, and vague generalities from the North.

“We’re talking about dozens of sites, hundreds of buildings, and thousands of people,” Dr. Hecker said Friday. The key to dismantling the sprawling atomic complex, begun six decades ago, Dr. Hecker added, “is to establish a different relationship with North Korea where its security rests on something other than nuclear weapons.”

Dr. Hecker cautioned that his team’s road map left room for many knotty points of negotiation — such as where to draw the line between civilian and military nuclear activities. At first, the Trump administration said the North must give up all enrichment of uranium, which can fuel not only bombs but reactors that illuminate cities. Last week, Secretary of State Mike Pompeo, testifying before the Senate Foreign Relations Committee, said for the first time that he needed some “negotiating space” on that question.