FOR THE SECOND time in four months, anti-Americanism has helped propel a leader to power in a country that for decades has depended on a close security alliance with the United States. South Korea's president-elect, Roh Moo Hyun, may be less cynical and opportunistic than Germany's Gerhard Schroeder, but he has a few things in common with him: a grounding in domestic populism, unfamiliarity with English and the United States, and a gut desire to shift the balance of power in his country's relationship with Washington. Like Germany, South Korea hosts U.S. troops and has depended on them for its defense; and in Korea, as in Germany, there is resentment toward what is seen as the Bush administration's overly aggressive campaign against "axis of evil" states -- especially Iraq and North Korea. Though the White House reacted angrily to Mr. Schroeder's campaign, and relations with his government remain chilly, Mr. Roh was greeted last week with statements of welcome and conciliation. That's partly because President Bush took personal umbrage at Mr. Schroeder's campaign-trail jibes. But it is also because the situation in Korea is far more dangerous. As North Korea flaunts its exports of long-range missiles and its efforts to produce nuclear weapons, both the Bush administration and Mr. Roh have a lot to lose if they cannot find a comfortable common ground.

The starting point for Washington will need to be acceptance that South Korea has greatly matured as a democracy and as an Asian economic power, and can no longer be treated as a docile client. During his campaign Mr. Roh complained that the United States often has failed to consult the South; one thing he had in mind was the Bush administration's adoption of a tough line toward the North's dictator, Kim Jong Il, even before the discovery of his renewed nuclear arms program. The administration's posture helped undermine the "sunshine policy" toward the North pressed by Mr. Roh's predecessor Kim Dae Jung -- though that initiative previously had largely failed to produce real change in the North's brutal and aggressive regime. Now Mr. Roh's determination to proceed with economic interaction and talks with the North could undercut the U.S. strategy of building a regional alliance to pressure Pyongyang to abandon its nuclear drive. With careful coordination and some compromise, Mr. Roh and Mr. Bush might be able to blend their tactics constructively. If not, they will simply empower Mr. Kim and invite more reckless behavior by his regime.

Mr. Roh has also promised to seek a change in the deployment of the 37,000 U.S. troops in South Korea. His public is seething over the accidental killing of two young girls in an Army training accident and the subsequent acquittal of the responsible soldiers by a U.S. court-martial. The Bush administration will need to look for ways to minimize the inevitable frictions that come with stationing troops in a densely populated foreign country; it also needs to talk more openly in Seoul about why those troops are necessary.

That is one area where Mr. Roh's help will be needed. The former human rights advocate once called for the withdrawal of U.S. troops from Korea; though he has changed that stance, he has done little to educate the younger voters who support him about the importance of the United States to South Korea's security. Mr. Roh frequently appears complacent about the military threat to his country from the North or about the great suffering of North Koreans. He also is reluctant to accept that North Korea's nuclear program and exports of weapons of mass destruction are not just a local problem, but a serious threat to global security, and thus to the United States. In the final heat of the campaign last week, Mr. Roh suggested that his government would not necessarily take sides between the United States and the North. But if he is to preserve the prosperous democracy that elected him, Mr. Roh must make clear that it still stands with the United States.