(Bloomberg Opinion) -- At the Demilitarized Zone between North and South Korea on Sunday, U.S. President Donald Trump put himself just where he likes to be: at center stage, showcasing his supposedly unmatched negotiating skills without net or supporting cast. The U.S. would have a better chance of reaching a lasting deal with Pyongyang if he now withdrew to the wings.The kind of personal diplomacy Trump favors can have its place. North Korean dictator Kim Jong Un cut off negotiations (and perhaps some of his negotiators) after being embarrassed by the failure of his last summit with Trump in Hanoi. Though the North hasn’t tested a nuclear weapon or long-range missile since then, its weapons programs have continued unchecked. If Trump’s handshake on the border gives Kim the cover he needs to agree to restart talks, it will have served some purpose.At the same time, the main issues that divide the two nations remain as intractable as ever. Kim wants sanctions on North Korea lifted as quickly as possible. The U.S. has resisted granting such relief until after the North has agreed to eliminate its nuclear and long-range missile stockpiles and production facilities, which Kim’s regime sees as critical to its survival. Riven by such irreconcilable goals, any new talks face bleak odds.If reports are correct, the Trump administration may be relenting slightly, aiming for a more phased approach that would begin with dismantling known production facilities and thus freezing the size of the North’s arsenals. The success of any such strategy will depend crucially on painstakingly negotiated details: which sites will be included, how the process will be monitored and verified, what the U.S. will give up in return, what comes next.The North, for instance, has previously raised the possibility of shutting down the Yongbyon Nuclear Scientific Research Center, its main nuclear complex. But Yongbyon encompasses a large area and several facilities; earlier partial suspensions of activity there, monitored by international inspectors, haven’t held. Any deal now would have to include not only all of Yongbyon but other suspected nuclear sites as well, subject to intrusive inspections on a scale the North has never accepted before. Kim would have to provide a fuller accounting of his nuclear and missile programs, and agree to a detailed timeline — however distant — to eliminate them entirely. For that matter, he’ll have to agree that that’s what he means by “denuclearization,” which he’s never publicly done.How much the U.S. concedes will have to be calibrated carefully against what exactly Kim offers. Largely symbolic measures, such as opening a diplomatic liaison office in Pyongyang or declaring an official end to the Korean War, are rightfully on the table. With appropriate safeguards, the U.S. could even allow some economic cooperation projects between the two Koreas, such as the Kaesong Industrial Complex, to start up again. Any broader sanctions relief must be tied to airtight, verifiable concessions by the North.Trump’s seat-of-the-pants style isn’t suited to such slow and frustrating bargaining. Indeed, his weakness for spectacle has already come at no small cost to U.S. credibility and leverage. Kim leads a murderous regime that runs vast gulags, assassinates opponents, counterfeits money, deals drugs and has launched audacious cyber-attacks. Yet, in three meetings now, and without having to give up anything substantial, he’s been treated by the world’s most powerful leader as a friend and visionary. He has every incentive to drive a hard bargain, knowing he can always appeal directly to Trump over the heads of aides and advisers.Any negotiations beholden to Trump’s whim and electoral calendar are likely doomed from the start. His administration has shown it’s capable of serious diplomacy. Its talks with the Taliban over withdrawing U.S. troops from Afghanistan have proceeded quietly and patiently, out of the spotlight and led by experts; they appear to be making steady if slow progress. Trump will have a better chance of reaching the blockbuster North Korea bargain he craves if he lets someone else close the deal.—Editors: Nisid Hajari, Mark Whitehouse.To contact the senior editor responsible for Bloomberg Opinion’s editorials: David Shipley at davidshipley@bloomberg.net, .Editorials are written by the Bloomberg Opinion editorial board.For more articles like this, please visit us at bloomberg.com/opinion©2019 Bloomberg L.P.