Since then, many observers have predicted that US hegemony (or in post-cold-war terminology, "unipolarity") is dissolving. Indeed, this a key motif in each decade, an accompanying chorus to (for example) the Soviet Union’s space programme in the 1950s; the "third-world" revolutions of the 1960s and 1970s; and the emergence of Japan, Europe and (now) China as major economic powers in the 1980s-2000s.
That one day the US’s dominance over the world will lessen is indisputable; but that another power will emerge in the foreseeable future that can rival it (as the Soviet Union did from a position of overall weakness) is less clear. A world of one dominant, and several medium powers, seems more probable. Paul Kennedy’s famous book, The Rise and Decline of the Great Powers (1989) - which speaks of "imperial overstretch", of the mismatch of political and strategic goals with economic and (not least) fiscal reality - set the scene for a whole range of such works; more recent examples include the work of the historical sociologist Michael Mann, (The Incoherent Empire), the veteran Guardian columnist Martin Woollacott (After Suez), the more meta-Hegelian speculations of Tony Negri & Michael Hardt’s Empire, as well as substantial chorus of Islamist triumphalists.
The financial press’s rich reportage of American domestic financial troubles - from the sub-prime crisis to the long-term dangers of the trade and current-account deficits - is, again as in earlier decades, a potent source for doom-laden projections of the fate of the behemoth. In the Gulf states, major investors are leaving the dollar, as they did the pound sterling in 1967. In August 2007, total holdings of US long-term securities fell by a record amount, $69.3 billion.
Robert S Singh of Birkbeck College, London, and co-author with Timothy J Lynch of a forthcoming book - After Bush: The Case for Continuity in American Foreign Policy (Cambridge University Press, 2008) - is not persuaded of these arguments. In a crisp summary of seven main points at issue, he lays out an alternative view:
historical perspective: we have been here before, not least in the late 1980s under the Ronald Reagan presidency; yet in the 1990s - be it in military expenditure, international influence, pop culture or information technology - the United States ran further ahead of all its rivals.
hard power: the US has by far the largest military budget and capability, and continues to have the strongest and must dynamic economy in the world, accounting even today for 20% of world output. It has a per-capita income of around $40,000, compared to a Chinese of $2,300.
international influence: the US has treaties with no less than eighty-four countries, and of the total of 200 in the world no more than five - Korea, Iran, Syria, Cuba, Venezuela - are outright enemies.
resilience: while US influence has certainly been battered in recent years - be it in the middle east, Europe or Latin America - it remains both resilient and (as the initiatives of French president Nicholas Sarkozy indicate) capable of recovering ground.
competition: the major rivals the US faces are much weaker than they appear: Russian military power is exaggerated; China’s economy and social fabric, not to mention political system, face increased strain.
global image: for all the hostility to the US over Iraq, or Guantànamo, people around the world continue to admire and desire aspects of the American way of life (and, not least, demonstrate in large numbers their desire to live there)
domestic aspirations: perhaps of greatest importance, there is no evident wish in the US - whether in the political elite in Washington, or in the Democratic Party, or in the nation as a whole - to abandon US primacy and exceptionalism. The new president of 2009 will only in some degree alter existing policies. Washington will continue to want to run, if not control, the world. We should not expect that much would change with the advent of Hillary Clinton or Barack Obama.
The issue of United States power is without doubt one of the half dozen most important questions in the world today. It is also one which, along with the others - the development of the world economy, the future of China, the limits on Russian reassertion, the spread and time-frame of the jihadi military campaign and, in the shorter term, the future of Iraq and the likelihood and consequences of a war with Iran - allows of no definite answer. The current data, historical precedent, and the assessment of probabilities and scenarios can offer guidelines, but little more; an added complication is that a never-to-be-discounted subjective factor, namely wishful thinking, often skews analysis in one direction or another.
At the same time, the back-and-forth of this debate may serve to obscure what, for any observer of US foreign policy, must remain four equally intractable questions.
First, what is the real impact on the US economy, and on the world economy as a whole, of the US campaigns in Iraq and Afghanistan? In a world where it is often said that politics and economics are closely intertwined, there seems (so far) remarkably little interconnection here. That the two wars have and will continue to consume vast amounts of money, and greatly reduce US credibility, is evident; yet, to date, the economic impact seems to be very small: the crisis in confidence in the US financial system is a result of debt mismanagement, mortgage and trade figures, not Iraq. The spread of inflation (and in particular the rise in the price of oil) reflect market conditions, not least Chinese demand and a shortage of refining capacity, not the reduction in Iraqi oil exports or the military and civilian costs of the war.
Second, why has it taken the US so long to recognise the crisis it is in in Iraq? Those working with the US and British forces in Iraq knew from spring 2004 at the latest that the stabilisation of Iraq would not work; from the latter part of 2005 - two or more years ago - there were many in Congress, including Democratswith close ties to the military such as Senator John Murtha, as well as combat personnel in Iraq, who were speaking out as the disaster in that country. True, great powers are notoriously unable to face up to realities (look no further than the US in Iran in 1978-79, or the Soviet Union in east-central Europe in the late 1980s); but after all the reports, debates, criticisms, and initiatives, the US today is as bogged down and as lacking in any coherent strategy as it was in 2004-05.
Third, what can be said of the extraordinary phenomenon of a major power that has gone to war in two middle-eastern states, Afghanistan and Iraq, and which is now contemplating a third, with Iran, but which is almost devoid of people with expertise or experience in, and on, these countries (see Godfrey Hodgson, "Washington discovers Islamabad", 27 November 2007)? Those specialists on Iraq, and Iran, who work in Washington or across the US have been systematically marginalised from policy discussions, their place taken by a motley gang of irresponsible and often corrupt political exiles, "terrorism experts", "security specialists", and other mountebanks. Many of those who pontificate about Iran in the US these days have never been there, and could not write a newspaper article, or academic essay, on the history, culture or politics of that country.
Fourth, a question that goes to the heart not only of recent US policy in the middle east but of the very character and sources of US foreign policy and decision-making itself is so simple that it is often overlooked in the welter of polemic and self-justification that besets the story, namely: why did George Bush decide to invade Iraq in the first place? The dispute over "weapons of mass destruction" and subsequent policy blunders has left this question unanswered and usually unasked, yet it remains unclear. Many have immediate, single-factor, analyses - from the "military-industrial complex", to "oil", by way of evangelical Christians or pro-Israel currents in the US, neo-conservative bellicosity after 9/11, and the simple desire of George W Bush to avenge a supposed assassination attempt on his father by Saddam Hussein in Kuwait, in 1993.
The best answer may be some variant of "all of the above". But as with the other mysteries of US empire and the US decline, no definitive answer to these questions is likely to become available in short order. The US empire, and all who love or hate it, or who merely seek to analyse it, must await the verdicts of history.