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“ALL warfare is based on deception”, wrote Sun Tzu, a Chinese military strategist who lived 2,500 years ago and remains influential in China today. The recent revelation by the Americans that China had destroyed an ageing weather satellite with a missile has certainly caused surprise and confusion. Why should a country so insistent that its rise threatens no-one stage such an open display of its ability to challenge American power in space?

China had been fuelling the mystery by neither confirming nor denying America's assertion on January 18th that the Chinese satellite was blown up about 500 miles above earth by a medium-range ballistic missile a week earlier. Then on January 23rd a spokesman for China's foreign ministry confirmed the satellite had been shot down. It was the first experiment of its kind by any country in more than 20 years (though there have been vague rumours of others). America itself, as well as the former Soviet Union, are the only other countries to have tested anti-satellite weapons.

Only two days after the apparently successful test, China's prime minister Wen Jiabao arrived in the Philippine city of Cebu to attend a regional summit. While there he called on fellow leaders to help China build a “harmonious East Asia”. The test, however, has created widespread unease. Some of Mr Wen's interlocutors in Cebu, including Australia, Japan and South Korea, have since joined a chorus of Western criticism.

The Americans, with their heavy dependence on military satellites and their commitment to help Taiwan defend itself from any attack by China, have the most to worry about. China has never admitted to having an anti-satellite weapons programme. But since the 1990s, Western experts believe China has become increasingly alarmed by the military advantage enjoyed by America thanks to its satellites. China is also worried that its strategic nuclear arsenal could be rendered useless by American efforts to build a missile defence system that includes space-based components.

America has long suspected China of developing anti-satellite technology. Last September reports emerged that China had been pointing high-powered lasers at American spy satellites passing over its territory. The apparent aim was to test an ability to blind them. A Pentagon report last May noted China's “rapid and relatively smooth rise as an emerging space power”, with plans for its own manned space station by 2020. China's intention, it seems, is to show that American supremacy in space is not unassailable.

It also has a more immediate goal. In 2002, China and Russia proposed a treaty banning the deployment of weapons in space or attacks against space-based objects. China's concern was that the American missile defence system would lead to increasing use of space for military purposes and fuel an arms race. The Americans have refused to negotiate, saying such a treaty would be unenforceable and would only give an advantage to countries (for which read, China) that are trying hide their efforts to develop weapons for use in space.

By destroying one of its own weather satellites, China might have been trying to force the Americans to the table. If so, it was a risky strategy. The test is likely to reinforce perceptions in America of China as an emerging threat. Japan and Taiwan will also be rattled. On January 22nd Taiwan—apparently trying to reinforce international opprobrium directed at its rival—said China had deployed some 900 missiles on the coast facing the island in recent years. Last August it had put the figure at 820.

The test is unlikely to foster closer co-operation between the American and Chinese civilian space programmes. Last September, in a sign of tentative warming between the two sides, Michael Griffin of NASA paid the first trip to China by a head of the American government's space agency. But China will have made no friends in NASA by littering space with fragments from the explosion that could threaten other spacecraft. “If your opponent is of choleric temper, seek to irritate him”, said Sun Tzu. China has certainly succeeded in that.