President Bush could hardly have picked a more critical time to host China's President Hu Jintao at the White House.

A flare-up in troubled waters between South Korea and Japan, faltering trilateral cooperation among the US, Japan, and South Korea, and the failure to persuade North Korea to come close to terms on its nuclear-weapons program all make China a pivotal player -- while raising questions about US strength and influence in the region.

"The United States can play a more profound role in stabilizing the region," says Moon Jung In, international relations professor at Yonsei University in Seoul. "China may be happy to see what's happening."

While the United States tries to persuade China both to reduce its yawning trade surplus with the US and get North Korea to return to six-party talks, a potentially explosive quarrel between South Korea and Japan is frustrating Washington's efforts to join its two northeast Asian allies in common cause on the nuclear issue.

"High-ranking officials of the South Korean government have been talking about Korean-US cooperation rather than trilateral cooperation," says Kim Sung Han, director of North American studies at the Institute of Foreign Affairs and National Security, affiliated with South Korea's Foreign Ministry.

"Trilateral cooperation is vital to resolving the North Korean problem," he says.

The tendency in Korea is to blame Japan for somehow wishing to assert its own role in the region, reminding both Koreans and Chinese of the history of Japanese imperialism in Asia, culminating in the conquest of much of the Chinese mainland and 35 years of colonial rule over the Korean peninsula.

Who lays claim to islands?

Memories of that history have leaped into the headlines as a result of a stand-off midway between Korea and Japan in what Koreans call the East Sea and the much of the rest of the world knows as the Sea of Japan.

The focal point is a cluster of 34 islets, basically uninhabitable, that both Korea and Japan claim as part of their national territory.

Korea calls the cluster "Dokdo," or "Solitary Island," while Japan calls it "Takeshima," or "Bamboo Island," and Japan also wants to give Japanese names to undersea rock formations surrounding the islands, basically volcanic rock thrust up from the sea.

The issue, simmering for years, reached a boiling point this week when Japan said it was sending two survey vessels to chart the waters around the islands, held by a garrison of Korean troops seen on Korean television manning anti-aircraft weapons and machine-guns as if to stave off enemy invasion.

Eager to prove his fearlessness in the face of the Japanese, South Korea's President Roh Moo-Hyun has ordered 18 patrol boats to form a blockade against the survey vessels.

"Some people are claiming territorial rights to former colonies that were once acquired through war and aggression," he told Christian leaders at a breakfast Thursday. Not just "good will," he said, as if preparing for war, but "wisdom and courage" were needed in such a crisis.

Shinzo Abe, Japanese government spokes-man, says the vessels are going there in defiance of a pledge of "stern action" by Korea's foreign minister, Ban Ki Moon, against any "provocation" by Japan.

Mr. Kim, of the Institute of Foreign Affairs and National Security, accuses Mr. Abe, an outspoken conservative who aspires to succeed Junichiro Koizumi as Japan's prime minister, of playing to the right-wing in refusing to address Korean sensitivities.

"Shinzo Abe has his own agenda," says Kim. "The Japanese are trying to increase their own role in the area of security. This is sending conflicting messages."

The sense here is that the US could rein in Japan but is reluctant to do so while cooperating closely with Japan on North Korea.

"The United States has been rather silent on these issues," says Kim Tae Hwan, research professor at Yonsei University. "Koreans have been very uncomfortable with the Japanese posture of aligning with the United States. Japan seems to disregard expectations from Korea."

While playing into the hands of China, the standoff over the islands also comes at an opportune moment in terms of South Korea's policy of rapprochement with North Korea.

Ministerial talks between North and South

South Korea's unification minister, Lee Jong Seok, goes to Pyongyang Friday for the first ministerial-level talks between North and South Korea in five months. He and his North Korean opposite number will have no trouble agreeing on the need to fend off what North Korea has already denounced as a "shameless" attempt at expansion.

It's a "very clear win-win" for both North and South Korea, says David Kang, a professor at Stanford University's Shorenstein Asia-Pacific Research Center. In the process, he says, the ruckus at sea "makes it look a lot as if Korea and China are cooperating more since they're both upset by Japan's moves."

Mr. Kang sees the standoff as "a distraction" that probably will not have "a fundamental effect on North-South Korean relations," but adds to the sense that six-party talks on North Korea's nuclear weapons are not likely to go anywhere.

"The US doesn't expect to make any progress on six-party talks," says Kang. "Nobody has a face-saving way out."

The visit of China's President Hu Jintao to the United States this week is yet another opportunity for chatter about the "Chinese threat.'' In the lead-up to his arrival, we have heard rising voices from Congress and from the administration on everything from China's currency manipulation and piracy of intellectual property to its military buildup.

Do not be deceived. There is no real appetite in either Washington or Beijing for confrontation over any of these issues, much less a serious exploration of the challenge that China presents to American global leadership.

Neither government can afford an escalation of tensions. Economically, we are too intertwined. Strip away the packaging on the $200 billion trade deficit with China and you will find American companies running global assembly lines that begin in Ohio, pass through Malaysia, and end up in southern China.

Strategically, the United States is painfully dependent on China to try to cope with the greatest security challenge in northeast Asia: North Korea's nuclear program.

Beijing is wedded to its doctrine of "China's peaceful rise.'' First formulated three years ago, it aims to keep things calm with the United States and most of its neighbors, buying time to manage the tightrope act of continuing high growth while preserving domestic stability.

In any case, Washington is too bogged down in the Middle East to do more than bark now and then about China.

"At the strategic level, the United States is really focused like a laser on the Middle East,'' and the Chinese like it that way, said Asian security expert Kurt Campbell. "They appreciate the fact that with the U.S. attention focused elsewhere, it allows China to play a larger role in Asia as a whole,'' he told a gathering last week at the Center for Strategic and International Studies in Washington.

Typically, while Washington is focused on Hu's visit, the Chinese defense minister is in the midst of an unprecedented Asian tour that will take him to North and South Korea and to Singapore, Malaysia and Vietnam. China's prime minister has just finished a swing through Australia, New Zealand, Fiji and Cambodia.

In my own travels through Asia recently, from South Korea and Japan in the northeast down to Singapore, Vietnam and Hong Kong in Southeast Asia, I found a stunning growth in China's influence. The question of how to deal with China's rise is high on every agenda.

Everywhere people are looking over their shoulder, worried about China's burgeoning strength and presence. They are equally fearful that the United States is abandoning the field to China. But they also don't want to choose between these two powers.

That is even true in Japan, where the popular media and politicians are full of talk about the Chinese threat. But look a little closer and you will also find a growing counter-movement, particularly in elite policy circles, warning against becoming separated from the rest of Asia. The battle for succession to Prime Minister Junichiro Koizumi, who is stepping down in the fall, is now being shaped around this issue.

The China-Japan rivalry tends to reveal the more muscular side of China's "peaceful rise,'' one that Americans rarely glimpse. In Vietnam, senior foreign policy officials recounted what happened when the Japanese came courting to gain Vietnam's backing for a resolution to give them permanent membership in the U.N. Security Council, a key goal of Japan's foreign policy. Japan is Vietnam's largest aid donor and a major source of foreign investment.

China and Vietnam have a long and stormy history as neighbors, including wars that go back centuries and -- more recently -- a brief invasion in 1979 that ended in defeat for the Chinese. Relations these days are relatively good, however, fed by growing trade, heavily in China's favor.

Hu, in his role as leader of the Chinese Communist Party, sent a special envoy to talk to the leadership of the ruling Vietnamese Communist Party. Sometimes, a Vietnamese official told me, the Chinese can be very indirect. Not this time. The message was simple: "Don't do it!'' The ``or else'' was left unspoken.

The Vietnamese compromised, supporting Japan's membership but refusing to co-sponsor the resolution. China was not pleased, but apparently accepted it.

For the Vietnamese, a senior official explained, they must engage in a "lot of fine balancing.'' Vietnam "can't stop engaging China'' but wants to make sure China becomes a "predictable'' power.

In Washington, when the cloud of rhetoric clears, that formula pretty much sums up the reality of U.S.-China relations, too.

SEOUL, Korea - The visit last month of North Korea's diminutive dictator Kim Jong Il to China is still making waves here in the South Korean capital.

The Chinese rolled Kim through showcases of their market reforms. The North Korean leader, who once denounced the Chinese for retreating from socialism, responded with dutiful words of praise for the Chinese model.

South Koreans applaud any evidence that Kim may be headed down a Chinese-style path. Like the Chinese, most South Koreans believe this may be the only way to ultimately persuade the North to abandon its nuclear weapons program.

But in conversations here with senior South Korean officials and others closely involved with North Korea, I detected unease, even alarm, at the growth of China's influence and presence in the North. Some talked darkly about a Chinese "takeover'' of the North.

South Korean mixed feelings about China are not new. But the Kim visit comes on top of a rapid broadening of Chinese economic ties to North Korea, described in detail in a new report issued by the International Crisis Group. Chinese trade and investment in North Korea has reached $2 billion annually. Bridges and highways in and out of North Korea are being built, making it easier to ship iron ore and other raw materials out.

Hundreds of Chinese firms are investing into North Korea, in some cases grabbing deals away from South Korean companies.

Is China willing to use this expanded influence to compel Pyongyang to give up nuclear weapons? Some in the Bush administration still cling to that hope. But the report argues strongly against that happening.

China may again drag Pyongyang back to the stalled six-party talks that it hosts. And it will move quickly to curb any North Korea provocation, such as a nuclear test, that could lead to war.

But China has an overriding interest in stability as well, opposing any attempt to destabilize the Kim government. The Chinese will cooperate to curb Pyongyang's laundering of counterfeit money through their banks, the report says, but will not shut down the North's banking operations in China.

South Koreans don't differ with China on the need to engage the North. Their own economic ties with the North are deepening. And Seoul too is consumed with the danger of triggering a war by trying to cut off the North's economic lifeline.

But South Koreans now also worry that China's deepening stake in the North will only perpetuate the division of the Korean Peninsula.

A South Korean businessman who is deeply engaged in dealings with the North argued to me privately that the North Koreans are unhappy with their dependence on Beijing and eager for an alliance with the United States. By refusing to deal directly with Kim Il Jong, he argued, "the Bush administration is pushing North Korea into the camp of China.''

We should explore such claims with a healthy dose of skepticism. The North Koreans are masters at playing the Chinese and South Koreans against each other, as they did with the Russians and Chinese during the Cold War.

More important, South Korean nervousness about China comes together with renewed interest in shoring up the strained alliance with the United States. This is partly behind a decision to negotiate a free-trade agreement (FTA) with the United States this year.

A free-trade agreement between the United States and Korea, one of the largest economies in the world, would be good for both economies. It should open more markets in Korea, removing a host of barriers such as restrictions on foreign investment. Korean officials, led by a young and ambitious American-trained trade minister, believe an FTA will spur a new round of needed internal reform and a jump in growth.

Anti-FTA protests were already taking place as I was discussing this with Korean officials. More are sure to come from those, such as farmers, most threatened by more open markets. But officials say the president and his government are committed to pushing this through.

Privately, Korean officials hope the FTA will also remind Koreans and Americans of the value of their alliance. It gives both sides something to talk about other than to dwell on their differences over North Korea. We should push hard from both sides to quickly finish an FTA deal -- and continue to talk quietly about our shared interests in maintaining a strategic balance in Northeast Asia.

What is South Korea's strategic posture in East Asia?

After the Korean War ended in 1953, South Korea and the United States established a political and security alliance that has lasted more than half a century. "For a number of decades, South Korea primarily defined itself as a U.S. ally, with the enemy to the north," says Donald Gregg, president of the Korea Society and a former U.S. ambassador to Korea. However, South Korea is now trying to create a new role for itself in Asia. Seoul is exploring a growing economic relationship with China--which passed the United States in 2003 to become South Korea's largest trading partner--and its policy of engagement and growing cooperation with North Korea is pulling it away from the United States. "All we know for sure is that South Korea's role is no longer junior partner to the U.S.," says David Kang, a visiting professor of Asian studies at Stanford University. "The days when they would just unquestioningly follow the U.S. are over."

Kang and other experts say Seoul is beginning to shift its focus towards increasing regional ties with its Asian neighbors. The U.S.-South Korea relationship, while still strong, is not as exclusive as it has been in the past. "South Korea is still an ally of the United States ... nevertheless, it has been the most active country in promoting East Asian cooperation and integration, and will probably continue to do so," says Charles Armstrong, professor of history and director of the Center for Korean Studies at Columbia University.

What are South Korea's biggest foreign policy challenges?

Dealing with North Korea while preserving its relationship with the United States, maintaining relations with Japan, and addressing potential long-term military or economic threats from China, experts say. But "the major issue for Seoul is overwhelmingly North Korea, and everything else gets filtered through that lens," Kang says. South Korea looks to its northern neighbor with the goal of eventual reunification, and therefore seeks economic cooperation and political engagement to smooth relations and slowly move down that path. The United States, on the other hand, is primarily seeking to prevent North Korea from gaining nuclear weapons, and has refused to engage with Pyongyang until that issue is resolved.

Other experts see a disconnect between how South Korea views its role in the region and how other nations see it. South Korean officials talk of playing a "balancing" or mediating role in regional disputes, including tensions between China and Japan and the nuclear standoff between the United States and North Korea. But South Korea's "actual ability to mediate and balance is limited," says Armstrong. And while South Korean President Roh Moo-Hyun has expressed hopes of building Seoul into a logistics and business hub for the region, existing tensions on the peninsula--including international fears that North Korea is amassing a nuclear arsenal--cloud any long-term economic plans. As things stand, South Korea has the world's 11th largest economy, but not a corresponding level of political clout.

How is South Korea dealing with North Korea?

Through a policy of active engagement. In 1998, Former President Kim Dae-Jung introduced the "Sunshine Policy" aimed at improving ties with North Korea while assuring Pyongyang that Seoul is not trying to absorb it. Since then, "the degree of economic interaction between south and north has substantially increased," Armstrong says. Kim and North Korean President Kim Jung-Il met at a historic summit in 2000, and increasing progress has been made on a range of issues, from economic--increased rail links and joint projects like the Gaesung industrial complex--to social and symbolic, including cross-border family visits and Korean athletes marching together under a single flag at the Olympics. Trade between the two countries reached $697 million in 2004, and South Korea is now Pyongyang's second-largest trading partner after China.

South Korea sees engagement with North Korea as yielding far more benefits than confrontation. "South Korea is reorienting itself toward reconciliation and eventual reunification of the peninsula," Gregg says. South Korean officials say reunification would reduce the burden on each side of maintaining huge armies, help improve living standards, draw international investment, create employment, and help avert the worst possibility: open war on the Korean peninsula.

What is South Korea's relationship with China?

South Korea is developing increasingly warm relations with its giant western neighbor. "There is a real fascination with China in South Korea, and the flow of investment, exports, students, tourists, and businessmen going to China from South Korea has exploded in the last several years," Armstrong says. Bilateral trade between Seoul and Beijing reached $90 billion in 2004, a 42 percent increase from 2003. The two countries also agree politically on issues ranging from opposition to Japanese Prime Minister Junichiro Koizumi's visits to the Yasukuni war shrine, to accord on how to deal with North Korea's nuclear ambitions. China is also choosing the path of engagement with North Korea, and helping Pyongyang find a "Chinese way" to develop: that is, increasing economic openness without sacrificing political control. "On the whole, [South Korea and China] see pretty much eye to eye on the major geopolitical issues," Kang says.

Beijing, like Seoul, is investing in North Korea, which has ample natural resources--including coal, iron, and gold--and a low-cost labor force. In 2003, Chinese investment in North Korea was $1.1 million; in 2004, it ballooned to $50 million; and in 2005, it was expected to reach $85-90 million. The volume of trade between China and North Korea reached $1.5 billion in 2005, making Beijing Pyongyang's largest foreign trading partner. North Korean leader Kim Jung-Il, who rarely travels, emphasized Beijing's importance to his country by visiting China in January.

South Korea is positioning itself to be closer to an ascendant China, but trying to do it without jeopardizing existing ties with the United States. South Korea's biggest worry, experts say, is being pulled into a conflict between the United States and China over Taiwan.

What's the relationship like between South Korea and Japan?

"Very bad at the moment in terms of public diplomacy and popular opinion," Columbia University's Armstrong says. South Korean wariness of Japan dates back at least to 1910, when imperial Japan invaded Korea and ruled it as a colony for thirty-five years. During the occupation, Japanese efforts to suppress Korean language and culture earned Korean enmity. During World War II, the Japanese practice of using "comfort women"--women from occupied countries, mostly Korea, who were forced to serve as prostitutes for the Japanese army--increased the anti-Japanese feeling.

South Koreans, and others across the region, are also infuriated by Koizumi's annual visit to the Yasukuni shrine. The site honors more than two million Japanese war dead, but includes the remains of more than a dozen convicted war criminals. South Korea also has disputes with Japan over territory. Both countries claim a group of islands--and the fishing and mineral rights around them--in the Sea of Japan that the Koreans call Dokdo and the Japanese call Takeshima. And many critics in South Korea and across Asia accuse Japan of whitewashing its wartime atrocities in its grade-school textbooks.

But much of the South Korean conflict with Japan may be for domestic political consumption, some experts say. "Under the surface, I would say the degree of interaction [between Seoul and Tokyo] remains high and, in the economic realm, is rather good," Armstrong says.

How is South Korea dealing with the United States?

While experts say most South Koreans still consider the U.S.-Korean alliance the backbone of their security relationship, time has passed and attitudes are shifting. A new generation of South Koreans, assertive and nationalistic, are less mindful of the Korean War--and less grateful for American intervention in the conflict that left nearly three million Koreans dead or wounded--and more resistant to what they see as a U.S. attempt to impose its values and Washington's singular focus on terrorism. The United States has opposed South Korean engagement efforts with North Korea, and has also moved to increase its ties with Japan. The Bush administration's foreign policy, including the war on terror, its punitive stance toward North Korean nuclear weapons, and particularly the invasion of Iraq, is highly unpopular in South Korea, according to opinion surveys there.

South Koreans are also increasingly demanding more control over their country's military and political affairs. In 2004, the United States returned several military bases to Korean control, and agreed to withdraw 12,500 of the 37,500 U.S. troops currently stationed in Korea by 2008. U.S. officials, including Defense Secretary Donald Rumsfeld, had been pushing for South Korea to take more of a role in the defense of the Korean peninsula, to free up U.S. forces for deployment elsewhere. But, all differences aside, Seoul is still eager to cooperate with the United States. South Korea, with some 3,000 troops in Iraq, is the third-largest member of the U.S.-led coalition there, behind the United States and Britain.

What is the recent history of the region?

Poised between China and Japan, fought over by the United States and Russia, the Korean peninsula long has played a central role in Asia's geopolitical affairs. After World War II, Japanese colonial rule gave way to U.S. and Soviet trusteeship over the southern and northern halves of Korea, respectively. The peninsula was divided at the 38th Parallel. In 1948, the southern Republic of Korea and the northern Democratic People's Republic of Korea, under Kim Il-Sung, were established.

In 1950, North Korean forces invaded South Korea, starting a conflict that brought in China on the North Korean side and a U.S.-led UN coalition on the South Korean side. While an armistice was agreed to in 1953, a formal peace treaty was never signed. In 1954, the United States agreed to help South Korea defend itself against external aggression in a mutual defense treaty. U.S. troops have been stationed in Korea since then. In addition to this important security relationship, shared interests in the last fifty years have included fighting communism and, since the 1980s, establishing a strong democracy and fostering economic development. However, in recent years strain has emerged on a range of issues, none more important than how to handle Pyongyang.