On Sunday, a US missile destroyer and a Chinese warship came within about 40 metres of colliding near a tiny set of Chinese-occupied reefs in the South China Sea. According to the United States, which revealed the incident on Tuesday, the USS Decatur was cruising close to the contested reefs when confronted by a Chinese destroyer that approached its bow and forced it to change course to avoid impact. 

The near miss is a worrying marker of escalating tensions between the two nations, which are locked in a worsening trade war. It was not the first such stand-off in the South China Sea – the Chinese military regularly tries to ward off the United States as it conducts freedom of navigation exercises near disputed territory occupied by China – but it is believed to be the closest. 

Australia’s defence minister, Christopher Pyne, said that China’s act of intimidation was “destabilising and potentially dangerous”. But Australia has refrained from joining the United States on such patrols. This is despite pressure from Washington – in February, Donald Trump said he would “love” Australia to participate.

Australia’s position is sensible. Its navy and air force patrol the South China Sea, and it is currently conducting two weeks of joint military drills in the area with Singapore, Malaysia, New Zealand and Britain. But it does not approach contested territory to dispute a nation’s sovereignty, and never has. Instead, it leaves this policing role to the United States, its closest ally, which has the world’s most powerful military.

This situation has been enormously convenient for successive Australian governments, which can volubly protest China’s assertions of sovereignty in the South China Sea without having to carry the risk of a confrontation. But this latest incident at tiny Gaven Reef is a further confirmation that this arrangement, which has underpinned Australia’s security in Asia for seventy years, is falling apart.

The United States’ ability to enforce order in the region rests on a presumption, shared by all in the Asia-Pacific, that its power will not and cannot be challenged, and that, should its power be contested, the United States would respond with force. Now China is just 41 metres from testing this notion. 

The decision to contest the USS Decatur was about much more than the sovereignty of a few submerged reefs on which Chinese communications and radar towers, wind turbines and a few administrative buildings now stand. China is furious at Trump’s escalating trade war. It has cancelled security talks with US defence secretary Jim Mattis, due to be held in Beijing later this month, and refused an American warship’s request to stop at Hong Kong. And so Beijing is edging closer to presenting Washington with the question: is the United States willing to fight a war to preserve its role in Asia? 

This protracted face-off does not need to end in conflict. The United States has various options for responding to Chinese provocations, including its ships sailing away from tense confrontations and its government condemning Beijing, as occurred in this case. But each encounter demonstrates China’s growing confidence, which in turn affects perceptions of US power. 

During the last such stand-off in the South China Sea, in May, China dispatched warships to warn off two US vessels near the Paracel Islands. The Chinese ships reportedly manoeuvred in a “safe but unprofessional” manner, but did not risk a collision. This time, the Pentagon described the operation against the USS Decatur as “unsafe and unprofessional”.

Australia’s approach to tension between China and the United States has been to try to preserve the existing regional order, even as it erodes. There are, as Mattis said of China–US relations on Monday, “two… great powers, two Pacific Ocean nations”. Australia has no choice but to develop a new understanding of its place in the region, including its relations with other rising powers such as India and Indonesia. 

For decades, the task for Australia was to support uncontested US power in Asia and to avoid the outbreak of local conflict. But the misses are drawing nearer to our shores – and these twin goals are becoming less compatible.