ONE OF THE substantive surprises of Thursday's presidential debate was the detailed exchange between President Bush and Sen. John F. Kerry on the critical but neglected subject of North Korea. Prodded by moderator Jim Lehrer, Mr. Bush touted and Mr. Kerry attacked the current U.S. diplomatic strategy for preventing North Korea from becoming a nuclear weapons power. Somewhat esoteric references to "six party" vs. "bilateral" talks and plutonium vs. uranium processing soon were flying back and forth, probably leaving a lot of viewers wondering what the difference was. Here's how we'd sum it up: Mr. Kerry faults Mr. Bush for undoing the diplomacy of the Clinton administration with respect to North Korea and intends to respond by undoing, in turn, what has been accomplished by President Bush.

Let's start with Mr. Kerry's indictment. The Clinton team painstakingly negotiated a deal under which North Korea supposedly froze its nuclear program and international inspectors monitored its known supply of spent nuclear fuel rods. North Korea received energy supplies from the West, and at the end of 2000, U.S. and North Korean officials were discussing a larger bargain concerning its weapons programs. In 2001 Secretary of State Colin L. Powell announced that the talks would continue, only to be publicly contradicted by Mr. Bush in front of the South Korean president. Two years then passed without negotiations: As Mr. Kerry put it, "while they didn't talk at all, the fuel rods came out, the inspectors came out . . . and today, there are four to seven nuclear weapons in the hands of North Korea."

Some truth-squadding is needed here: While the CIA concluded that North Korea may have built one or two nuclear weapons before Mr. Bush took office, and while U.S. intelligence agencies believe the fuel rods have been reprocessed into plutonium, there is no certainty that North Korea has built more nuclear weapons. To say so is to make the same sort of reach that Mr. Kerry faults Mr. Bush for making in his statements about Iraq's nuclear program. Nevertheless, the senator is right about the policy failures. In part because it has been paralyzed by internal feuding between hawks who favor "regime change" and advocates of negotiations, the Bush administration has been feckless in facing the North Korean threat.

Mr. Bush made two points in his defense. One is that President Bill Clinton's deal with North Korea collapsed after Pyongyang was caught cheating: While "freezing" its plutonium, it was secretly pursuing another bomb program based on enriched uranium. The other is that despite an overall diplomatic stalemate the Bush administration has succeeded in persuading China -- a neighbor that arguably has more leverage over North Korea than the United States -- to join a five-nation alliance that commonly seeks disarmament. It is this innovation that Mr. Kerry would undo. He says he would return to the bilateral negotiations pursued by the Clinton administration.

Mr. Kerry says his strategy would make room for China, too. But Mr. Bush's prediction is probably right: As soon as the United States agrees to bilateral talks, the North Korean regime will refuse further sessions of the "six party" negotiations that have been underway, relieving China, South Korea, Japan and Russia of responsibility for pressuring Pyongyang and leaving the United States to make a deal alone. Lacking the tools of China -- which controls North Korea's energy supplies and could cause its regime to collapse simply by loosening border controls -- the United States would once again face the choice of offering distasteful bribes to a murderous dictatorship or threatening an almost unthinkable war. Mr. Bush doesn't have a good record on North Korea, but he has mapped a possible way out of this difficult bind -- assuming, that is, that a diplomatic solution is possible. Apart from purely partisan motivations, Mr. Kerry's rejection of it makes little sense.

This is one in a series of editorials comparing the records and programs of the presidential candidates on important issues. Others can be found at