"It must be irritating to find yourselves the recipient of every demand, to be called upon in every crisis, to be expected always and everywhere to do what needs to be done.” That is how Tony Blair addressed the American people in 1999, when genocide was raging through Kosovo. But - in a graphic illustration of the shift in global power - today's anti-genocide campaigners are focusing their energy on a rising China rather than on a United States bogged down in Iraq and Afghanistan.

Steven Spielberg's boycott of the Beijing Olympics over China's role in Darfur was an act of conscience that attracted global attention to a tragedy of unimaginable proportions. However, while Spielberg's own boycott was inspired, it would be wrong for the British Government to follow suit.

While the call for boycotts can be helpful in putting Beijing under pressure, there are three reasons why a boycott by a government could be counter-productive.

First, governments cannot treat their links with China as a one-night stand - they are in a long-term relationship with Beijing whether they like it or not. The Olympics was always meant to be a coming out party for the world's newest superpower. The recent media furore reminds the Chinese - to paraphrase Spiderman - that with global power comes global responsibility.

It is clear that complex problems such as Burma, Zimbabwe and Darfur won't be solved in a six-month window. That is why the Government must look at China's policies within a historical context, and have a strategy for influencing Beijing beyond the summer of 2008. China used to plead poverty when asked to get involved in global problems. It no longer has that luxury, now that its state-owned companies have colonised the world from Angola to Iran, and Venezuela to Zimbabwe. In response to global pressure, Beijing has gradually played a more active role in the North Korean and Iranian nuclear problems, and by sending 4,000 peacekeepers to participate in UN missions.

Even on issues where China has been at odds with the West - such as on humanitarian intervention - its position is becoming more nuanced. When the West wanted to intervene in Kosovo, China opposed it on the ground that it contravened the “principle of non-intervention”. On Iraq, it abstained. And on Darfur, after blocking measures at the United Nations for many months, China actually voted for a UN mandate for peacekeepers when it was chairing the Security Council. It is vital to keep the pressure on China to take more responsibility but we should not ask governments to treat the nuclear option of a boycott as if it were a conventional weapon.

Secondly, the Government will have more influence by encouraging Beijing to use its leverage on Khartoum, rather than questioning China's right to have an economic presence in Sudan. There is a tendency to abuse China for all its economic activities in the developing world, rather than making a fair assessment of its impact on particular policies. Western governments must develop a more calibrated response, using sticks and carrots to incentivise China to play a more responsible role.

“We should make it clear that we are not asking China to stop importing Sudanese oil,” says Andrew Small, a foreign policy expert who has studied China's role in rogue states. “But rather we are asking them to support more extensive UN sanctions, and to stop exporting weapons to Sudan.” Instead of threatening a boycott of its own, the Government could have more impact working with NGOs to agree a set of ambitious but credible demands that they would press China to meet in private and that NGOs could campaign around in public.

Spielberg might, for instance, have threatened to boycott the Olympics unless China forced Sudan to accept immediate deployment of the agreed peacekeeping troops, rather than because China was simply a key Sudanese ally. This is just sensible politics: if China is attacked indiscriminately - no matter what policies it pursues - it will see no point in co-operating at all.

Thirdly, we must recognise that China can't solve every issue on its own. In Darfur, the West has skilfully hidden behind Chinese vetoes - but we can see from the situation on the Chad-Darfur border how Western countries are reluctant to live up to their responsibilities. For example, last September the UN Security Council authorised the deployment of a European Security and Defence Policy (ESDP) force to Chad and the Central African Republic. But there was little enthusiasm among European states for the mission, and a shortage of helicopters prevented its initial deployment in December. Western NGOs must highlight the indifference of Western governments rather than letting them shift all the blame on to China.

The Olympics presents Western governments with an opportunity to develop a policy towards China that is focused on global issues rather than a craven pursuit of commercial deals. Spielberg's boycott has rocked Beijing by playing into China's constant fear of being portrayed as a threat by the West. But Western governments now need to follow it up with concrete and deliverable demands rather than empty grandstanding.

Mark Leonard's book What Does China Think? is published on February 18

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