ON ITS FACE, the multinational agreement on North Korea's weapons program announced yesterday is a surprising piece of good news. For the first time, Pyongyang's brutal communist dictatorship formally agreed to "abandoning all nuclear weapons and existing nuclear programs," and said it would return "at an early date" to the nuclear Non-Proliferation Treaty and its accompanying international safeguards. In return, the United States agreed to take steps to normalize relations with the North and, together with South Korea, Japan, Russia and China, provide it with aid -- including at some "appropriate time" a new light-water reactor for generating electricity. Fulfillment by the North of its commitment would mean an extraordinary breakthrough after more than a decade of failed efforts by the United States to contain one of the world's most serious proliferation threats.

The risk, however, is also considerable: If North Korea's new promise is not a serious one, the agreement will only forestall more concerted outside pressure on the odious regime of Kim Jong Il, while sustaining and enhancing the lifeline of food and energy it receives from its neighbors. History suggests that it is that outcome, rather than genuine nuclear disarmament, that the North is betting on. In 1994, after reaching a similar deal with the Clinton administration, it froze activity at one nuclear complex but secretly launched a program to develop a bomb by other means. It was eight years before the Bush administration discovered the deceit and suspended the "agreed framework."

To comply with its latest pledge, the Kim regime would have to reveal and disassemble the unknown number of nuclear weapons that, by its own account, it possesses. It would have to dismantle both the Yongbyon reactor, which produces plutonium, and hidden uranium-enrichment facilities. But it hasn't yet admitted the existence of the uranium plants, and it's hard to conceive of an inspections process that could fully verify the disarmament of a totalitarian state that holds untold thousands of its citizens in concentration camps, earns much of its foreign income from counterfeiting and drug trafficking, and prohibits foreigners from visiting many parts of the country.

North Korea's agreement to yesterday's statement excuses it from the potential displeasure of China, which brokered the talks and supplies Pyongyang with food and energy. It allows for the continuation of rapidly improving relations with South Korea, including provision by the South of large new supplies of electricity. In accepting Mr. Kim's pledge, the Bush administration avoids looking like the obstacle to progress and keeps the diplomatic focus on the North's disarmament. For the first time in 41/2 years, the administration appears to be pursuing a coherent strategy, instead of veering between confrontation and negotiation amid endless internal debates. Those diplomats and opposition Democrats who have argued strenuously that a workable deal can be struck with Pyongyang will see their theory tested. We hope that it works, but also that Mr. Kim is not given much time to deliver. If he is sincere, a concrete disarmament plan could be agreed on relatively quickly. If he is not, talks that have already lasted more than two years will drag on, to the disadvantage of U.S. and global security.