BEIJING - A message from President Bush to North Korean leader Kim Jong Il will be delivered Monday in Pyongyang -- via two Chinese officials. Beijing now meets quarterly with Mr. Kim, the most contact the unpredictable North has with any outside party. Whether Vice Foreign Minister Wu Dawei and Vice Premier Hui Liangyu will surprise Kim Jong Il and exert real pressure is unclear.

With an international diplomatic effort under way a week after North Korea tested seven missiles, China has proposed informal six-party talks as a way to move the process along.

That is less than the US hoped for from China. But since China insists that it will veto any UN sanctions against the North, the US will accept such talks, according to envoy Christopher Hill.

All told, Beijing would appear key to shaping how the world deals with the defiant Kim. Yet from the moment Kim launched his missiles, China has denied it has clout; it politely insists that the US has the central role.

Since 2003, China has embarked on a historic effort to prop up and aid North Korea -- a state it had the frostiest relations with for more a decade. Now, $2 billion in aid gives Beijing unprecedented access -- something China is reluctant to squander, to "mix aid and diplomacy," as a Chinese scholar here puts it.

"China's influence on North Korea is more than it is willing to admit, but far less than outsiders tend to believe," says a recent report by the Seoul branch of the International Crisis Group.

To outsiders, it appears that a rising China -- running a lifeline of energy and food to its poor comrade - ought to have clout in Korea, as it holds more carrots and sticks than anyone. It seems axiomatic that Beijing can simply apply ancient Chinese wisdom and modern Chinese might to stop Kim's nuclear ambition. Both states are communist, wear green and red uniforms, fought the US together, and share borders and history. China is the only country with easy access, as well as trade and tourism, to the North.

"China does have leverage, but it is afraid it may overplay its hand," says Joseph Cheng, head of the political science department at City University in Hong Kong.

Since Kim Jong Il's July 4 missile shots, voices from Sandy Berger, President Clinton's security adviser, to John Bolton, US ambassador to the UN, have argued that "China is the key" to dealing with North Korean belligerence. It has become nearly a mantra in Washington. Twelve months ago, it was an article of faith in senior White House circles, misplaced or not, that China would deliver a deal with Kim to dismantle his nuclear program. Yet this did not happen.

Instead, with the US preoccupied in Iraq, China embarked on a quiet policy of self-interest: to strengthen North Korea. That policy helps to maintain the North as a "buffer state" between China and South Korea.

China does not want the North to collapse, and for US troops to fill the vacuum and appear on its northeast border. China has hosted Kim, and moved relations away from a bad patch in the 1990s, during the North's epic famine, when China asked for cash payments for food instead of barter.

In the past two years, Chinese officials have told Kim that he can reform his state along socialist lines just as China did. China has indicated it will help with economic aid, while he retains complete political control. To now castigate Kim could wreck that formula, sources say.

In the larger sense, Kim's launch of missiles, most of which could hit long-time nemesis Japan or US bases in East Asia, puts China in the position of choosing between its North Korean comrade and an evolving consensus in the international community. So far, China has tried to please both sides.

"I'm concerned that China isn't recognizing how serious this issue is," says Zhang Liangui, head of foreign studies at the Central Party School in Beijing, in a rare dissent. "China is taking a rigid position. Yet we have long said that if China wants to be viewed as a responsible superpower, it must not be isolated in the international community."

Adding to Beijing's problems is an unresolved ideological struggle in China -- where "neo-orthodox" hard-liners who maintain contact with North Korea want China to support its revolutionary posture. There is also genuine puzzlement in Beijing over how to deal with Kim, whose founder-father, Kim Il Sung, reputedly warned him many times that China would attempt to take over his regime one day.

"I hear often that China is the key, which involves a set of policy steps Beijing can take that will bring about the outcome the allies want," says Russell Leigh Moses of People's University. "But I have yet to see anyone show how if China does X, Pyongyang will do Y."

The White House seems to have abandoned its 2003 optimism that China will harness Kim. China may agree that a nuclear peninsula and a regime that test-fires rockets is not desirable. But it isn't clear on how to force Kim to open his highly controlled state and allow international inspectors to flood in, witness his system of gulags, and bring in potentially subversive material -- all to dismantle a nuclear program he's cherished for decades. The White House seems to understand this.

Scott Snyder of Stanford University argues the US is using the same strategy that it used with China in closing down Kim's accounts in Macau. China was forced to choose between the international regulatory authority, or North Korean money-laundering behavior.

Sunday, Undersecretary of State Nicholas Burns argued on FOX News Sunday that "It's time for China to exert its influence that it does have on North Korea." Also on Sunday programs, US and Japanese officials claimed they might have the votes to support a Japan-backed resolution for sanctions against the North.