In three decades of diplomatic relations between China and the United States, ties between the two countries have been a combustible mix of contradiction and cooperation. It has always been a rocky love-hate relationship, full of ups and downs but ultimately underpinned by economic interests. China has learned how to handle the US' hot-and-cold political attitude while the US has learned how to press China for compromise.

But since US President Barack Obama concluded his visit to China last November, during which collaboration was placed at the top of the agenda, relations have been clouded by conflict once again. But this time the fundamental dynamics of the relationship appear to have shifted irrevocably.

China is offended by what it sees as a succession of US hostilities aimed at checking China's rising global influence.

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Since the start of 2010, it has been riled by the Obama administration's explicit support of Google, the $6.4 billion arms deal with Taiwan, tariffs imposed on Chinese tires and steel pipes, heightened pressure to allow the renminbi to appreciate and, last week, the meeting between Obama and the Dalai Lama.

Looking at each of Obama's decisions at face value, his policies do not differ from those of his predecessors. But his timing -- one blow quickly followed by another -- has infuriated China's leaders. The importance of saving face in Chinese culture is well known. Slapping the Chinese face once, twice, three times, four times might be considered several strikes too far.

But reasons for the latest tension run much deeper. China has emerged from the financial crisis a more confident and assured nation, willing to be more vocal in the geopolitical arena. China has seen Western industrialized nations struggle to wriggle free of the recession as it recorded an economic growth of 8.7 percent in 2009, exceeding the government's target by 0.7 percentage points.

Trade has also shown a strong recovery, narrowing from a 25-percent contraction in the first half of last year to a 13.9-percent decline for the whole year. Although China's trade deficit declined 34 percent, the total amounted to $19.6 billion. Auto production increased 44 percent, to as much as 13.8 million units; auto sales rose 48 percent, to 13.7 million units.

The steady recovery in China has also driven a growth in demand for raw materials. Iron ore imports rose 41.6 percent in 2009, boosting resource-based economies such as Australia, Brazil and Russia.

So, even though China has been the biggest beneficiary of the economic recovery, it has aided in the recoveries of other countries. Its total GDP may lag far behind that of the US, but its contribution to global GDP growth already exceeds that of its biggest competitor.

It has long been said that when the US sneezes, the rest of the world catches a cold. We are now nearing the time that if China gets a headache, the world will suffer a migraine.

Obama is keenly aware of the economic interdependence that binds China and the US, and the importance of their healthy relations to global stability.

However, it is not difficult to understand why he has adopted a tougher approach toward China in recent weeks. Under fire at home, particularly following the Democrats' loss of the US Massachusetts Senate seat in January, he must be seen as assertive in dealing with China. Obama knows the rise of China's counter-balancing power is inevitable. But as a president of the world's only superpower, he must do his utmost to slow its speed.

The rapidity of China's advancement in the aftermath of the financial crisis, and the simultaneous weakening of the US' clout, has undoubtedly shocked many in the US. They knew it was coming, but not at such a meteoric rate.

China's ascension to superpower status is still a long time away. Over the next 10 to 20 years, China will need to show a degree of tolerance when it feels it is being unfairly lectured by the US, but also take certain measures to express its anger.

Historical, cultural and ideological differences between China and the US, coupled with the US' desire to maintain its world dominance, mean that their relationship will not always be peaceful.

But as long as Sino-US conflicts stop at the political and economic level, the damage to the global economy will be contained. When both sides stand in opposition, there is a bottom line: no direct confrontation.

The biggest stumbling block is the Taiwan question. But even in this hotly disputed contest, one will leave the other room to maneuver. The US will receive funds from the arms sales to Taiwan; China will not use force against that island province.

On Tibet, the US will not recognize a separation of the autonomous region and will verbally acknowledge it is part of the Chinese territory. We saw last week that Obama, in a move designed to limit offense to China, received the Dalai Lama in private and refrained from making comments in public. China, for its part, summoned Jon Huntsman, the US ambassador to China, to register its displeasure but stopped short of allowing it to impact on economic ties.

It was a case of mutual compromise on both sides. China adopted its effective tactic of protesting vocally but showing its willingness to compromise if the US maintained a low-key attitude toward the Dalai Lama. It would certainly have taken firmer action if Obama had conducted the meeting in a more public manner or issued any declaration.

Economically the US needs China for its huge market and low-cost exports. China needs the US because it is the biggest consumer market in the world and it possesses technology China requires.

In the spheres of foreign relations and politics though, China and the US will be far from intimate. The Obama administration will need to realize that China is prepared to be more expressive in its objections to what it perceives as US provocations. That's the nature of the love-hate relationship.

The author is head of the School of Contemporary Chinese Studies at the University of Nottingham.

(China Daily 02/22/2010 page6)