In the words of George W. Bush, conducting foreign policy is "hard work." As the immensely ambitious strategic vision of the Bush Administration enters its fifth year, numerous indications of strategic fatigue are in evidence. There is talk of troop withdrawals from Iraq and Afghanistan, even though the insurgencies are not subsiding in either country. The vigor for prosecuting the Global War on Terror is slowing, and, more importantly, the zeal for instigating regime change in other countries--North Korea, Iran, Syria and perhaps Venezuela--has visibly waned. The much scorned, traditional diplomatic processes shepherded by the State Department have returned. Congress is slightly less supine. Changes are evident in both substance and style as Condoleezza Rice demonstrates a newfound preference not to get out too far in front of the creaky wheels of multinational institutions that were the bane of administration activists. The administration's bark is minimized, and much of the bite seems gone.

Has superpower fatigue set in? Clearly so, to judge by the administration's own dwindling energy and its sober acknowledgment that changing the face of the world is a lot tougher than it had hoped. Of course, some degree of wear and tear is normal five years into any administration, regardless of policies. But fatigue emerges in direct proportion to the ambitiousness of the undertaking. From its early days, this administration adopted a strategic vision and peremptory posture whose implementation would prove exhausting under the best of circumstances. Administration documents and statements have regularly indicated that "we are at the beginning" of "a long war" fought globally in well over one hundred countries, probably "lasting for decades", until "victory over terrorism" is achieved. Even more, this all ties in with "the ultimate goal of ending tyranny in our world." The task is Sisyphean, the enemy generalized, the goals unclear, the scope open-ended.

The taxing character of U.S. foreign policy betrays signs of morphing into "imperial overreach." And there should be no doubt that we are talking about empire here, albeit in a new form. Neoconservatives embrace the term openly, while the ultra-nationalists, headed by Dick Cheney and Donald Rumsfeld, do not disavow the concept. The extent of U.S. global reach--the overseas military installations and complex base-rights agreements that often dominate our relations with small nations, the peripatetic military-command representatives who overshadow ambassadors, a broad variety of active military presences, a worldwide intelligence and strike capability--is well documented. The U.S. global "footprint"--a revealing word regularly employed by the Pentagon without irony--is massive and backed by the world's most powerful military machine in history. While different in structure and intent than the British, French or even Roman imperial presence, current U.S. ambition for projection of power is sweeping. And pursuit of this goal generates ever newer challenges that quickly contribute to strategic fatigue.

Most empires ultimately founder on economic grounds. But the short-term economic cost of the administration's policies, while high, has not yet become unbearable. Still, there are a number of longer-term indicators that do raise worries about American economic capacities on into this century: massive domestic debt, an ever greater trade imbalance, the extraordinary and broadening gap in domestic wealth between rich and poor that has no parallel in other industrial nations, the growing outsourcing of jobs, and the rise of economic competitors who are hungry for a place in the sun. But it is the immediate political cost of the expansion of empire that is fatiguing, even before the economic cost fully bites in.

"Superpowerdom" imposes the psychological burden of being on the firing line all the time, everywhere--and almost alone. The unprecedented unilateral character of U.S. exercise of global power was of course a conscious choice, reflecting a strong desire to liberate Washington from wearying, nit-picking and encumbering consultations with other world players. It bespeaks a desire to simplify the decision-making process and to clear the decks for action. Ad hoc allies were to serve primarily as diplomatic window-dressing and hopefully to pick up some of the bills. But the broader backlash to U.S. unilateralism and its resultant isolation and loneliness it has imposed on Washington were not entirely anticipated.

The administration's foreign policy has been conducted on at least three levels, all of which had an impact on its global reception: strategic, tactical and stylistic. The strategic level could be summed up by the Pentagon's use of the term "full spectrum dominance." Although it specifically refers to desired military capabilities, the choice of words leaves little doubt about its political implications as well. The United States is the globally pre-eminent power, resolved to prevent the emergence of any peer. The task is the indefinite extension and projection of U.S. power to shape the world with little resistance. Entirely predictably, ambitious regional great-power centers--the European Union, China, Russia, India and Brazil to name a few--instinctively objected to this open bid for American hegemony. And their distaste at the strategic level complicates policy acceptance at the tactical level, since U.S. tactics, however well conceived in any given situation, nonetheless contribute directly to an unwanted American strategic project. Thus the removal of Saddam Hussein, or even the Taliban, whatever the merits of each case, could not be viewed in isolation but only as key building blocks in a grand U.S. strategic agenda. Similarly, as distasteful and worrying as Tehran's regional and nuclear ambitions might be, neither Russia nor China (nor even Europe) are entirely willing to see Washington crush Iran's independent global posture in a way that leaves the United States entirely free to do its bidding in the Gulf.

Finally, at the level of style, the American dispensation with diplomatic finesse in the lead-up to Iraq and the Global War on Terror alienated many allies in nearly all continents. Washington was willing to make occasional nods to formal multilateralism as long as events closely followed the American script, as with the "coalition" in Iraq. But in the end the gratuitous alienation of many U.S. allies has exacted a measurable and ongoing political cost on U.S. capabilities, now dramatically acknowledged with Condoleezza Rice's new look at the State Department.

But as unpalatable as the uncompromising manner was to so many, it was surpassed by a much more distressing phenomenon: the emergence of a unipolar world. The world is quite unaccustomed to the phenomenon of unipolarity and is still trying to cope with its many implications: in politics, economics, energy, war and the fate of international institutions. And, more importantly, the world is now busily engaged in the process of chipping away at that unipolarity wherever it can.

The reality is that no serious player on the international scene can embrace a unipolar world. All states value options. It may well be that if there has to be any sole superpower, most might prefer it to be the United States--at least that appeared to be the case up to five years ago. But what matters is that few accept the status quo. There is genuine global concern with the overwhelming character of American power, against which, it is implied, serious resistance is futile. Major states prefer the more complicated, traditional balances among powers that limit the exercise of excessive power by any state. A multipolar world multiplies the power of smaller states, enabling them to form ad hoc coalitions capable of deterring the actions of the dominant power when need be.

There would have been diminished temptation for the Bush Administration to embrace unilateralism as a policy except that the emergence of a unipolar world made unilateralism an option. Our unrivalled power beginning in 1991 was heady brew, liberating the ideological forces of neoconservatism that could, for the first time, credibly speak of imposing an American agenda on the world order.

Yet it is an old political science cliché that a unipolar system over time invariably engenders its own counterweight. Nature abhors a sole superpower; other powers eventually bandwagon against it. So our present strategic fatigue may stem less from the immediate commitments in which we are embroiled and rather more from an unceasing necessity to maintain that sole superpower status against all comers--because that is what the very nature of unipolarity requires.

This exhaustion is perhaps most sapping at the domestic level: Americans are dying in meaningful numbers abroad; there is a lurking fear that the world is not safer, and maybe more dangerous, because of Iraq; Americans prefer to be liked abroad and are uncomfortable with their isolation; U.S. international business is unhappy; and the budget is soaring out of sight, even if its costs haven't yet touched the private pocketbook.

The intensified nationalist and neoconservative agenda within the administration, with its dramatic policy consequences, has greatly divided the nation. While the shock of 9/11 helped create a certain national "can-do" spirit of solidarity against foreign terrorists, that sentiment was rapidly depleted by Bush's broader response to 9/11. The resultant ongoing bitter domestic divisions require the administration's foreign policy architects to drag along a large and hostile domestic minority even before dealing with an unsympathetic world as well.