This is the relationship that will define global politics

Martin Jacques is a visiting professor at Renmin University, Beijing (THE GUARDIAN, 15/06/06):

At the time of 9/11 and the invasion of Iraq, the US stood supreme with barely a challenge visible on any meaningful time horizon. Almost five years on, we can clearly see both the inadequacies in the then-prevailing common sense, and the fallacies intrinsic to the neoconservative view of the world. There are, of course, always limits to power, even if they are not visible. The last five years have made the limits of American power plainly visible.

It is Iraq that has exposed those limits. The idea of US omnipotence always depended on its overwhelming military power, and the neoconservatives saw the latter as the key to a new era of American ascendancy. Iraq has demonstrated the limits of military power when it comes to subduing and governing a society. This failure has curbed the desire to intervene elsewhere: even if military action is contemplated in Iran, which now seems less likely, there will be no Iraq-style invasion and occupation. The idea that Iraq would be a precursor to a new kind of American empire - as advocated by Niall Ferguson, for example, in his book The Colossus - is dead in the water. Overwhelming military power, moreover, is subject to other limitations. What underpins power - all kinds of power - is economic strength, and in this respect the US is the subject of both a short-term crisis - the twin deficits - and a longer-term constraint, namely the fact that it accounts for a declining share of global GDP.

Iraq also demonstrated another profound shortcoming in the neo-conservative worldview. It was seen as both important in its own right, and as a means of reorganising the Middle East. But this approach, magnified by the failure to subdue Iraq, led to an overwhelming preoccupation with the Middle East and, to a much lesser extent, central Asia, and the implicit relegation and neglect of US interests elsewhere. Perhaps superpowers always overreach themselves; arguably it is an occupational hazard. But history will surely judge the invasion of Iraq to have been a huge miscalculation and the moment when the geopolitical decline of the US, following the end of the cold war, first became manifest.

In contrast to five years ago, the likely identity of the next superpower has become crystal clear. It is no longer just a possibility that it will be China; on the contrary, the probability is extremely high, if not yet a racing certainty. Nor does the timescale of this change have us peering into the distant future as it did five years ago. China is already beginning to acquire some of the interests and motivations of a superpower, and even a little of the demeanour. Beijing feels like a parallel universe to the US, and certainly Europe. There is an expansive mood about the place. China is growing in self-confidence by the day.

And with good reason. There is no sign of China's economic growth abating, and it is this that lies behind its growing confidence. The massive contrasts between China and the US, both socially and economically, are enjoined in the argument over America's trade deficit with the China. The latter is deeply aware that its future prospects depend on the continuation of its economic growth and this remains its priority. But no longer to the exclusion of all else: China is beginning to widen its range of concerns and interests.

This has received most airplay in the context of China's search for secure supplies of oil and other commodities. To this end it has been acquiring a growing diplomatic presence in regions of the world like Africa and Latin America, making the US increasingly nervous about China's intentions. This is understandable. China's growing economic clout and connections mean that it will increasingly offer an alternative to the US as an economic partner, and China is making it perfectly plain that it will not insist on the same kind of political strings as the US. We are only at the beginning of what will over time become a growing competition for the hearts and minds of the developing world. In his speech at Yale University during his recent visit to the US, Hu Jintao set out - for the first time in such a forum - the Chinese view of a harmonious world based on the idea of Chinese civilisation. The most dramatic changes, though - albeit sotto voce - have been taking place in east Asia.

Though far from Europe's line of vision - it has had little stake in the region since the postwar collapse of the European empires there - east Asia is pivotal to China's prospects and the future of Sino-US relations. For the last decade, China has been busy overhauling its approach to the region and involving itself for the first time in its multilateral arrangements. This process has been steadily accelerating, especially since the Asian financial crisis.

The key has been China's developing relationship with Asean, which comprises the nations of south-east Asia and is by far the most important regional institution. China has made the running - ahead of Japan - in the creation of a nascent broader regional framework. While in north-east Asia, it has used its role in the talks over North Korea to forge a much closer relationship with South Korea. All very reasonable. The result, however, has been the slow but steady marginalisation of the US, a process exacerbated by the fact that America's attention has been overwhelmingly directed towards the Middle East, which in the long run is actually far less important.

It is a combination of these developments that perhaps helps to explain why Hu Jintao's visit to the US was not accorded the full status of a visiting head of state. It was a deliberate snub, reflecting the unease with which Washington views the rise of China and its possible implications. But this was more a matter of pique than substance. It is now too late for the Bush administration to seriously rethink its relationship with China, but this will surely be top of the agenda for the next administration. But it admits no easy solution. Whatever the Pentagon may suggest, the Chinese have been careful to avoid posing a military challenge to the US, which lay at the heart of the cold war antagonism between the US and the Soviet Union. Moreover, again unlike in the cold war, the two countries now find themselves highly economically interdependent. Yet China's continued rise is bound to provoke growing disquiet and anxiety in Washington. It is this relationship that will lie at the centre of global politics; if that is not apparent at the moment, it will be very soon.