Israeli troops are in Lebanon again and Beirut burns once more. The Afghan war no longer looks securely won, putting heavy strain on the tiring British ally as the Taliban launches its own insurgency.

The Iranian government seems less than impressed by the Euro-American diplomatic coalition -- which has at most lukewarm and token Chinese and Russian support -- that is seeking to bribe and cajole Tehran out of its nuclear ambitions. The price of oil remains punitively high, and those Persian Gulf "allies" who have so long enjoyed U.S. protection are not inclined to boost their output fast enough to cut it.

Russia is making a come-back; India and China are on the march. Old NATO allies in Europe are not nearly as loyal as they were. Even the trusty Brits are having second thoughts. A poll published in the Daily Telegraph earlier this month found 76 percent of Brits saying that President Bush was doing a "terrible or pretty poor job." The newspaper's comment on the poll concluded "there has probably never been a time when America was held in such low esteem on this side of the Atlantic."

That venerable mosquito Fidel Castro suddenly finds new partners in Venezuela and Bolivia in his 47-year-old war against the Monroe Doctrine and U.S. hegemony in its hemisphere. America's unipolar moment, the 15-year era of undisputed U.S. mastery that followed the collapse of the Soviet Union, seems to be drawing to a close almost as soon as it began.

Is it really that bad? Joseph Joffe, a veteran German commentator who knows the United States well, edits and publishes Germany's most serious weekly Die Zeit, thinks not. In a new book, "Uberpower," Joffe reminds us of the unique strengths and capabilities that the United States retains as the world's overwhelming military, economic, technological and cultural power, "a state of affairs unknown in human history."

But as the fastest gun in the West, the United States must always be ready to uphold its reputation so that others will continue to believe it, even when the odds are against it and the terrain and weapons are not of the Uberpower's choosing.

No nation or movement is fool enough to take on the United States toe-to-toe, so they use the asymmetric weapons of the weak, terrorism and guerilla war and defensive diplomatic groupings like the China-inspired Shanghai Cooperation Group, whose not-so-discreet agenda is to lever the Uberpower out of Central Asia.

The United States finds its other diplomatic goals blocked by unusual combinations, so the Doha Round of the world trade talks bogs down and the Free Trade Agreement of the Americas withers on the vine and the United Nations starts to feel like a hostile environment.

And yet much of the Uberpower's ability to shape the world to its own taste and comfort depends on its prestige and its credibility, and these are eroding significantly because as the Uberpower, the United States has to be ready to engage on almost every front at once. It still keeps troops in the Balkans and South Korea, mans new bases in Central Asia and the Caucasus, is now being pressed to re-engage in Somalia and help the United Nations and African Union in Sudan's Darfur province. And it is not easy for a civilized nation to ignore the moral argument to intervene even in hopeless cases -- if not the Uberpower, then who?

The benefits of being Uberpower are not matched by the costs, unless the Uberpower engages in ill-conceived and ill-conducted actions that demonstrate its vulnerabilities. This is now the case, and an Uberpower whose prestige is waning is one that must either restore its position through bold action or accept a diminishing status, or swiftly acquire new capabilities that can meet the damaging new weapons of its tormentors. Air power and smart weapons are not enough against ruthless guerillas and terrorists; the Uberpower has to learn new tricks.

The fact is that rather like the British empire of the 19th century, with its reliance on sea power and better technology rather than the massed conscript armies of France, Russia and Germany, the status of today's Uberpower rests on a great deal of bluff. The Uberpower has too many commitments and too few troops, and that bluff is now being called.

The British made up for their own troop shortages by building a large Indian Army under the Raj, which provided the troops that policed Asia and the Middle East. The U.S. military, trying with painful slowness to re-learn the lessons of counter-insurgency war, has yet to consider the idea of its own Foreign Legion of volunteers, offering 20 years of service in return for U.S. citizenship.

And yet something of the kind may be required if the Uberpower's prestige is to be maintained, because Uberpower status rests on credibility. Others must believe it, and now that al-Qaida and Iraqi and Afghan insurgents and Iranian Ayatollahs all demonstrate with considerable expense that they do not believe it, the United States is trapped in a series of difficult battles to restore prestige on ground of the enemies' choosing.

Joffe agrees with two of the most thoughtful American practitioners in this field, with Dr. Henry Kissinger's dictum that power must be wed to consensus, and to Prof. Joseph Nye's "soft power" argument; that hard power means forcing someone to do what you want, whereas America's genius has traditionally been to use the soft power of getting the other guy to want what you want. Broadly speaking, the seduction of America's soft power was rooted in freedom of politics and economics and religion; free press, free markets, free trade and the American dream.

The Uberpower must now confront a world in which a lot of its enemies hate that idea of religious freedom, and authoritarian regimes who do not want political freedom, and victims of globalization at home and abroad who see little hope for them in the new economic freedoms. And old allies in Europe and Asia question whether the American consensus, as interpreted by the Bush administration, the neo-cons and the Christian Right, still works for them.

Much of Joffe's book is targeted at the Europeans, as ungrateful free riders on the Uberpower security system, which is a fair point to make -- although Brits and Poles have cause to grumble that their stalwart loyalty has been ill-rewarded. But the real point of his book is that the United States is stuck with its Uberpower status, and will have to make it work again by ensuring that others can believe in it again. And right now, that credibility is low.

(Uberpower: The Imperial Temptation of America, by Joseph Joffe. $24.95, W.W.Norton and Co.)

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