North Korea's announcement this week of plans to test a nuclear weapon is hardly surprising. The six-party talks to negotiate an end to its nuclear program are dead, and the North faces escalating financial and economic sanctions by the United States and its allies.

Experts have long debated the real motivations of the North in developing nuclear weapons. Some contend that the nuclear program, even the latest pronouncement, is simply a bargaining chip to gain security guarantees and economic aid. Others see a long determination to become a nuclear state.

The North Korean leaders may have begun the nuclear program as leverage. But the U.S. invasion of Iraq seems to have hardened their conviction that the only way to protect their nation and their regime is to join the nuclear club. The North Koreans want to become a Pakistan rather than an Iraq.

Still, officials in Pyongyang hesitated to cross the provocative line of visibly demonstrating their capability. Pressure is being mounted to get them to back down from their pledge. But for a variety of reasons, they apparently believe the timing for a test is now optimal.

First of all, they hope to blame the Bush administration for their decision. In the statement issued this week, the North Korean government argued that alleged American war plans justify a nuclear test, a position that reflects the views of the North Korean military.

Second, the North anticipates the test will be successful. Although a plutonium weapon is more complicated than a uranium bomb, it is quite likely that the North now has sufficient confidence in a Nagasaki-style primitive bomb. This success would be an object of pride for an otherwise failing state, and bolster its claim to the status of a world-class military power.

Third, the North Koreans see their potential enemies tied down and unable to respond effectively. The Bush administration is locked into a disastrous war in Iraq, and about to be weakened even more if the Republicans lose the upcoming midterm elections. In South Korea, the government of President Roh Moo Hyun is already a lame duck and politically paralyzed.

Fourth, Pyongyang may bet that China and South Korea, the two principal sources of trade and economic aid, would not join the United States and Japan in any real sanctions against the North. The July missile tests by North Korea provoked international uproar and led to a U.N. resolution. But the real impact has been minimal.

Finally, the North may calculate that testing will facilitate Japan's efforts to become a "normal'' nation with a broader military role in the region. That prospect could increase tensions in Northeast Asia, especially between Japan and China, and that, the North may believe, is not necessarily bad for it.

The United States, South Korea and China must act together to show that these calculations are misguided and that the North will pay a painful price if it goes ahead. Certainly this severely tests the troubled American alliance with South Korea and the emergent partnership with China. But Pyongyang's miscalculations also offer an opportunity to repair the strained alliance and create a new structure of security cooperation in Northeast Asia.

It is no secret that Seoul and Washington have been at odds over how to deal with North Korea. But the test announcement has already accelerated a shift in South Korean opinion. Rather than holding the United States responsible for the current impasse, most Koreans now see North Korea as the instigator of crisis.

South Korean officials understand that without reinforcing the alliance now, no policy toward the North can be effective. The United States and South Korea should urgently agree on common action plans -- including a shutdown of investment and economic assistance from the South to the North -- and make those consequences clear to Pyongyang.

The planned visits of newly installed Japanese Prime Minister Shinzo Abe to Beijing and Seoul next week offer a similar opening to turn threat into opportunity. Abe intends to repair tattered ties to those Asian neighbors. Now the three Northeast Asian powers can demonstrate that a nuclear test will not lead to increased tensions but to the complete isolation of the North.

The danger of escalating actions that could lead, again, to war on the Korean peninsula is grave. The North Koreans should be assured that the door to a diplomatic solution remains open to them. But they must also understand that by profoundly misreading this moment, the North Korean leadership now stands completely alone in Northeast Asia.

Reprinted by permission.

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.