Past negotiators say full-fledged talks would require the United States to have a disciplined process and a team across government agencies working out the nuts and bolts of any agreement. They urged the administration to get ready for such a heavy lift if it was prepared to make a serious attempt.

“It’s going to take time to get this underway under any circumstances. I would get going right away,” said Wendy Sherman, who served as North Korea policy coordinator for the Clinton administration and lead negotiator with Iran during the Obama administration.

“When we did the Iran negotiation, we wrote an entire agreement, over 100 pages, before we began the negotiation, so we had a sense of what we were trying to achieve,” Sherman said. “It was incredibly detailed and incredibly technical. There’s homework to be done.”