A Chinese H-6K bomber patrols the islands and reefs in the South China Sea. Credit:Xinhua/AP Fairfax Media spoke to a wide range of key security experts about how China's military growth could directly threaten Australia. Opinions varied but there was broad concern that China's increasing ability to project military power south had significant implications for Australia, especially as its role as a US-allied base would grow if US-China relations deteriorated. Malcolm Davis, an expert in Chinese military modernisation at the Australian Strategic Policy Institute, said H-6K bombers armed with cruise missiles could come significantly further south from the Spratlys. "The Australian government should factor this in, for the simple reason that, with the rebalance to Asia, there are going to be US forces in Australia," he said. While aerial refuellers already allowed bombers to strike at long range, they were an encumbrance, Dr Davis said. If Beijing developed its planned H-20 stealth bomber, its ability to approach Australia without the need for easily detectable refuelling planes would provide a major advantage.

A photo released by China's Xinhua News Agency shows a pair of Chinese civilian jet airliners after landing at the newly created island in a test of its airstrip. Credit:Xing Guangli "Then it gets really interesting," Dr Davis said. "It's their stealth against our counter-stealth capabilities." Australia would send F-35 Joint Strike Fighters out of RAAF Base Tindal in the Northern Territory to counter any bombing threat. Both Dr Davis and Stephan Fruehling from the Australian National University said Australia might require stronger air defences across the north. Runways and a control tower on one of the islands in the South China Sea. Defence announced on Friday it was sending more than 1000 troops – including frigates, surveillance planes and Hornet fighters – at short notice to Derby in the north west for Exercise Northern Shield, which would test their ability to respond quickly to a security crisis.

Dr Fruehling, who was an external adviser on the recent Defence white paper, was sceptical about the usefulness of long-range bombers during a conflict, but said China could conduct aggressive patrols off north-west Australia similar to those it conducted near Japan and as Russia's had done in northern Europe. China is not going to permit this without responding "China's trying to send a signal that, if Australia gets involved directly or indirectly in joint patrols in the South China Sea, Australia shouldn't assume that its distance protects it," Dr Fruehling said. "Those patrols [off Western Australia] would be quite useful to send that signal." Mr Shearer, now at the Washington-based Center for Strategic and International Studies, said a bigger concern for the Australian mainland was "China's rapidly growing and modernising strategic missile force". Alongside North Korea's long-range nuclear missiles, these could put at risk bases in northern Australia and joint facilities such as Pine Gap. "We are going to have to get much more serious about missile defence," he said.

This meant upgrading the new Air Warfare Destroyer warships with ballistic missile interceptors and considering land-based missile defence. Analysts broadly agreed that, even in situations well short of war, China could use its ability to project power south to coerce Australia, including by dissuading it from becoming too reliable a base for the US. "The strategic purpose of the ADF for the future will be to protect Australia as a base for long-range allied operations," Dr Fruehling said. Alan Dupont, chief executive of the security consultancy the Cognoscenti Group, said: "We are a redoubt or a sanctuary if you like for the US. China's strategy, I have no doubt, is to prevent any increased use of Australian facilities by the US." Dr Davis agreed: "China is not going to permit this without responding."

Several experts, including Benjamin Schreer from Macquarie University, said the artificial islands were too vulnerable for launching long-range bombers during a conflict. But Professor Schreer said they would create a naval "bastion" in the South China Sea "from which you can project naval power, particularly submarines, towards the Indian Ocean including towards Australia". Former Defence official and now head of Strategy International, Ross Babbage, said the US had limited basing options in Asia. "As a consequence, the Chinese know damned well they can target these facilities and do a lot of damage in the early hours of a clash. That could include, and many people think would include, some places in Australia." Paul Dibb from the ANU said Chinese military technology, while improving, was being widely overhyped. Euan Graham of the Lowy Institute was also cautious, saying it would be "extremely audacious" for China to try military action against a high-end power such as Australia given it hadn't performed combat operations since its brief border war with Vietnam in 1979.