One of the less publicized but perhaps most important matters before President Bush on his recent trip to South Korea for the annual Asia-Pacific Economic Cooperation summit was that of relations between the United States and the host country. Although South Korea has long been a close ally of the United States, relations between the two have cooled in recent years, and the alliance has come under great strain. Bush's trip did not set a new direction for the alliance, which has been drifting for the past few years.

There is a way to reverse this cooling in relations, I believe -- to promote U.S. strategic interests in the region, including denuclearization of North Korea; to retain U.S. influence there; and to strengthen a long-standing alliance. What is needed is an effort to widen the "North Korea problem" from one of nuclear weapons to one of unification.

Controversy over the fraying U.S.-South Korea alliance focuses almost exclusively on cultural or emotional issues. In the United States there are some who feel that South Koreans are insufficiently grateful for the steadfast U.S. support to South Korea, particularly for the American lives lost in defense of the South during the Korean War of 1950-53 and for the extensive economic and military aid since. Others feel that rising anti-American sentiment in South Korea reveals the naivete of a younger generation of Koreans who are insufficiently worried about the North Korean threat.

But the problems in the alliance are not a result of emotion, naivete or ingratitude. Indeed, even if none of those emotional and cultural issues existed, the alliance would still be in dire need of revision. To find the best path forward for both the United States and South Korea, we need to focus on the real issues.

The main factor straining the alliance is the unresolved Korean War and the continued division of the peninsula. This has created differing long-term strategic concerns for the United States and South Korea.

For South Korea, the key issue is not North Korean nuclear weapons -- it never was. South Korea's overriding concern is how to resolve the issue of national unification and integrate North Korea back into the world's most dynamic region, whether or not there are nuclear weapons. All other South Korean foreign policy issues take second place.

In contrast to Korea's regional issues, U.S. concerns are global and military. For at least the next several years, the United States will be mainly concerned with countering potential terrorist threats. Distracted by the overwhelming focus on anti-terrorism, homeland security and other issues, the United States has viewed its Korea policy as a narrow extension of its anti-terrorism policy, focusing almost exclusively on denuclearizing the North. These different strategic priorities have led to severe strains between the two allies, despite the desire of both to maintain a close relationship.

The United States can improve its position in East Asia, as well as solidify its alliance with South Korea, by widening its focus beyond North Korean denuclearization and coming out strongly and enthusiastically in favor of Korean unification. Although the United States rhetorically supports unification, it has been noticeably passive in pursuing policy to that end.

Such a policy shift would achieve many U.S. goals and would strengthen our alliance with South Korea in the process.

First and foremost, denuclearization is far more likely to occur with a change in North Korea's regime and a resolution to the Korean War than it is without resolving that larger issue. Until now the United States has put denuclearization first, without making much progress. Folding the nuclear issue into the larger issue would provide far more leverage on both questions and potentially create new or broader areas for progress.

Second, such a policy would provide grounds for agreement between U.S. and South Korean policymakers from which they could cooperate and work together, rather than against each other. Exploring the best path toward unification will require both economic and military changes in the North -- changes that will provide the United States with more flexibility to rebalance its own forces in the region.

Finally, it would put the United States in a solid position to retain goodwill and influence in Korea after unification -- something that is far from ensured today, when many South Koreans are skeptical about U.S. attitudes and policies toward the region. If the United States is seen as a major source of help for unification, it is far more likely that the post-unification orientation of Korea will be favorable to Washington.

This would be a major policy change for the United States, but given the importance of the region and of the Korean Peninsula, it is the best path to follow.