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.