As the Bush administration winds up its eighth year, the talks with North Korea about its nuclear weapons program stand as a piece of unfinished business and a challenge for the next administration.

His position has taken a180-degree turn. He started off by listing North Korea as part of an “axis of evil” and declaring that he loathed its leader, Kim Jong Il. He reneged on a Clinton administration deal in which North Korea froze its nuke program in return for economic and energy assistance. He refused to negotiate until North Korea had completely abandoned nukes.

Then came a long, intermittent string of six-nation talks sponsored by China and including North Korea but no one-on-one talks with the United States.

Finally, the president reversed himself and permitted direct negotiations. The result, after years in which North Korea produced plutonium and tested delivery systems, was a denuclearization agreement and the current slow process of stage-by-stage reciprocal concessions. North Korea has shut down its plutonium production and presented a lengthy but possibly incomplete listing of its nuclear works. The United States has begun sending oil and has taken North Korea off its list of terrorist states.

Things are going reasonably well, says Selig S. Harrison, a leading American North Korea watcher and summer resident of Islesford, but concessions remain to be made by both sides. Mr. Harrison, director of the Asia program of the Center for International Policy in Washington, says a major stumbling block that needs to be removed is a 2002 CIA charge that North Korea was conducting a secret nuclear weapons program at a uranium-enrichment plant. North Korea denies the charge, and U.S. negotiator Christopher Hill has said it was never clear that such a plan existed. But former U.N. Ambassador John Bolton, and others who oppose the denuclearization diplomacy have revived the CIA charge.

Mr. Harrison wrote in February in The Washington Post that “Pakistan’s Dr. Strangelove,” Abdul Qadeer Khan, arrested three years ago for running a global nuclear market, has been shielded ever since from official interrogators. They want to ask him about former Pakistani President Pervez Musharraf’s assertion that Mr. Khan gave North Korea centrifuges for uranium enrichment experiments. They want any dates, places, quantities and invoices if he confirms the report. An obvious solution would be for the International Atomic Energy Agency to interview Mr. Khan.

In any case, the diplomatic progress represents an achievement by Secretary of State Condoleezza Rice.

Critics will continue to pressure the next president to quit the talks and go back to threats of military action. He shouldn’t.