Concerns are growing that a serious incident could soon occur between the Australian Defence Force and the Chinese military as strategic tensions grow in the Indo-Pacific, as Australia's Defence Minister warns the world is witnessing the biggest military build-up since World War II.
The ABC has revealed HMAS Parramatta was recently closely tracked and challenged by the Chinese military while transiting through the contested waters of the South China Sea and East China Sea.
As details emerged of Australia's latest interaction with the People's Liberation Army (PLA), a US warship conducted a freedom-of-navigation operation (FONOP) in the South China Sea on Wednesday by sailing within the 12-nautical-mile boundary imposed by Beijing on the Paracel Islands.
Australia is yet to conduct a US-style FONOP to challenge Chinese claimed territory and features in the South China Sea, but military observers believe the tempo of ADF activity in the region is high.
In May, a Chinese jet fighter intercepted an Australian surveillance aircraft in the South China Sea, first firing flares and then cutting in front of the P-8 Poseidon and releasing a bag of chaff.
Professor Don Rothwell — an international law expert at the Australian National University — warns the prospect of a miscalculation in the South China Sea involving Australia and China is growing.
"I think it's becoming increasingly difficult because it is clear that there is a pattern associated with Australia's activities now [that is] very much aligned with the way in which the United States conducts similar activities," Professor Rothwell told the ABC's Afternoon Briefing.
"Australia, to a degree, is isolated and, yes, the risk of miscalculation is one that is very live."
Professor Rothwell's concerns are backed by Nationals MP Darren Chester, a former minister for veterans' affairs and defence personnel.
"What concerns me is there's more likely to be some incident at a future point resulting from a level of misadventure or miscalculation or mistake being made than an actual act of aggression," Mr Chester said.
"We need to be very careful and need to make sure we are working closely with our allies. I think it is really important that we try and de-escalate these situations wherever possible.
"At the same time, we have every right to be there. The Australian navy is incredibly professional, incredibly well-trained and incredibly capable and they are just doing their job."
The Defence Department has declined to comment on the recent interactions between HMAS Parramatta and the Chinese military, but Defence Minister Richard Marles said encounters with foreign militaries were not unexpected.
"What we anticipate is interactions with other militaries. We anticipate interactions with the PLA. None of that is a surprise," Mr Marles told the ABC during an interview in Washington DC.
"What we seek is that those interactions are done in a professional and safe manner."
Defence Minister warns of 'most dangerous' period
Mr Marles used a meeting with his US counterpart at the Pentagon to discuss growing anxiety about China’s military expansion.
Defense Secretary Lloyd Austin said the shared vision of Australia and the United States, for a free and open Indo-Pacific, was being challenged.
"China's disruptive and destabilising actions threaten to undermine our values, our interests and our shared conviction that all states should be free to choose their own paths without coercion or intimidation," he said.
Mr Marles had earlier opened a Washington office of the Australian Strategic Policy Institute (ASPI), which has been criticised by Beijing as an anti-China think tank.
Also in attendance were the heads of Australian security agencies the Australian Security Intelligence Organisation (ASIO), the Australian Secret Intelligence Service (ASIS), the Australian Signals Directorate (ASD) and the Office of National Intelligence (ONI).
"This is probably the most-dangerous period that I've lived through," Mr Marles said.
"What's the conclusion to that? What have the conclusion to military build-ups of that kind been in the past? Have they ended with happy endings?
"That's what keeps me awake at night."
Mr Marles is on a four day visit to Washington and previously argued the US-Australia alliance needed to avoid "a catastrophic failure of deterrence" in the Indo-Pacific.
