Simon Tisdall

A hosepipe fight between US and Chinese sailors in the South China Sea has put a temporary dampener on the feelgood glow created by Hillary Clinton’s recent Beijing visit. China’s foreign

ministry angrily accused the Pentagon on March 10 of breaking maritime law, distorting the truth, and engaging in “totally unacceptable” behaviour.

Chinese military officials went further, hinting that the Impeccable, an unarmed US ocean surveillance vessel intercepted on Sunday off Hainan island by five Chinese ships, was on a spying mission. If so, this would be unsurprising. Among other facilities, Hainan houses a base for China’s ballistic missile submarine fleet. It is an obvious target for US military intelligence gatherers.Beijing has repeatedly protested against US naval incursions into its “exclusive economic zones”. The US has not ratified the UN’s 1982 law of the sea treaty that created the zones, and maintains its ships operate in international waters.

Clinton certainly devoted considerable energy in Beijing to stressing the need for joint efforts to fight global recession, climate change, and nuclear proliferation. With an uncanny choice of metaphor given recent events, the secretary of state declared: “We are truly going to rise or fall together. We are in the same boat, and, thankfully, we are rowing in the same direction.” All the same, this latest spat could serve as a timely reminder of the many fault lines that run through Sino-American relations, which even a post-Bush policy of closer bilateral engagement and co-operation cannot wholly hide. If the Obama administration was in danger of glossing over these points of friction, the Impeccable provided a reality check. Accelerating military competition in the Asia-Pacific region is one major area of concern. China’s latest 14.9% annual increase in military spending, its recently confirmed plans to build aircraft carriers, and its evident intention to project “blue water” naval power eastward into the Pacific, foretell a challenge to US dominance by mid-century.

The two sides recently agreed to resume regular military contacts, broken off last year after Bush sold $6.5bn in arms to Taiwan. But the agreement did not prevent the Impeccable incident. Speaking recently, Admiral Timothy Keating, head of US Pacific Command, complained of a continuing lack of transparency and candour on the Chinese side. This week’s Chinese crackdown in Tibet, Beijing’s snarling rejection of State Department criticism of its human rights record, and its ongoing obduracy on trade and currency issues, present additional tripwires for advocates of unconditional engagement.

China’s blocking last week of an American move in the UN security council to condemn Sudan’s expulsion of aid workers from Darfur showed how, China, far from rowing together with the US in the same boat, is not even on board. Next month’s G20 summit in London, when Obama and President Hu Jintao will discuss co-ordinated action to beat the recession, will be the biggest test yet of a relationship holed below the waterline.