NEW YORK: Even given the inherent ruthlessness in the imposition of emergency rule in Pakistan, there was something almost poignant last week about President Pervez Musharraf appearing before the press and practically imploring the United States to understand the reasons for his move.

Dictators don't usually do that. They don't go in for a lot of public self-justification in Cuba or China or Burma, although none of those countries are remotely as tied to the United States and dependent on American support as Pakistan is.

Still, as the Bush administration searches for ways to restore some semblance of democracy in Pakistan - and a semblance of democracy is the best that has generally been managed there over the decades - the question remains: How can the United States best promote its own values around the world, which the Bush administration declares to be one of its major goals?

China, in this sense, emerges as the world's most important remaining one-party dictatorship, but, unlike Pakistan, where Washington simply says, "hold elections," the encouragement of democracy in China is more complicated and less obvious, but just as hotly contested a question as ever.

Indeed, a recent book, which argues that on human rights grounds, American policy toward China has been both a failure and a fraud, is making a considerable stir among China policy makers and scholars in the United States.

The book is "The China Fantasy" by James Mann, a former correspondent in Beijing for The Los Angeles Times and now author in residence at the Johns Hopkins School for Advanced International Studies.

Mann's thesis, adamantly rejected by many, though not all, experts on China, is that the American policy of what is called "engagement," pursued with some fits and starts by every administration since Richard Nixon's in the 1970s, has not delivered on its main promise, which was Chinese democratization.

When, for example, the Clinton administration ended linkage between trade benefits for China and progress in human rights, the argument to skeptical members of Congress held that delinkage would lead to more economic growth, more economic growth to the emergence of a middle class and the emergence of a middle class to real political reform.

Andrew Nathan, a China expert at Columbia University who supports the Mann thesis, put it this way in an interview: "The strategy of engagement has been incredibly successful in supporting the stability and prosperity of China and allowing the regime to survive as an authoritarian, repressive regime, but the American people are not being told that that is the strategy."

According to Nathan, everybody involved in the debate would be perfectly delighted if China were to turn into a stable democracy, but in the meantime policy makers are actually pretty happy with the regime in China that they have.

"That's because they know who to call in Beijing and who to talk to about problems like currency, trade, North Korea and Taiwan," he said. "There's somebody in charge and they're basically pretty cooperative with us."

In many respects Mann's book reprises an argument that has been raging among China policy makers and experts since Nixon restored relations with China in 1972.

The questions have always been: How much should the United States publicly criticize China for its numerous, egregious human rights violations and how much does the human rights goal have to be accommodated to China's power and importance?

But because Mann's book accuses China policy makers of a kind of broken promise, it seems to have generated an especially angry response on the Internet and in such specialty journals as The China Quarterly, which published a lengthy exchange between Mann and David Lampton, a leading figure on China who is also at the School for Advanced International Studies.

Mann also touches what may be a sore point in stressing that, with a few exceptions - Nathan one of the most prominent among them - China scholars and policy makers have tended to be rather silent on Chinese human rights abuses, though many of them say that they bring these matters up forcefully with Chinese officials in private.

And this, in turn, has long been part of a complicated debate about how to apportion priorities on China. Administration after administration has come to power in Washington pledged to be tougher on China only to retreat once it needed China's cooperation on other matters.

The China specialists' retort to Mann builds on two elements, one of which is the need for that cooperation. The bilateral relationship faces tough times, some of them say, not least on trade where the ever-growing deficit is bound to lead to calls in the United States for sanctions.

In addition, some China experts are concerned over the trend toward what has come to be called "strategic hedging" on China, building relations with countries on China's periphery as a way of containing what conservatives in the Bush administration regard as a looming military threat from China, a threat that a lot of experts (including Mann) believe to be largely imaginary.

On human rights in particular, some China scholars criticize Mann for concentrating so much on political reform that he has failed to appreciate the enormous beneficial changes that have occurred in China over the past decade, where a middle class of perhaps 200 million to 300 million people has come into existence enjoying a degree of personal autonomy that would have been unthinkable 15 or so years ago.

"Jim's image of China is stuck in the Tiananmen crackdown period," said David Shambaugh, a China scholar at George Washington University. "He thinks China today is the same as China in 1990."

Among Lampton's arguments is that Mann overestimates the centrality of the United States to political developments in China, that if democracy takes hold there it will be because of developments in China itself, not because of pressures from outside.

"The Chinese middle class is not now a wedge pushing for democratization," Lampton said. "In the short run they may be more afraid of the underclass than of the elite, and the middle class is key.

"I think we should be supportive of underlying economic developments that will build a middle class, but there are limits to what U.S. policy can accomplish," Lampton said. "Jim seems to be more implicitly optimistic that if U.S. policy were different, there would be a Chinese reality more to our liking."