On Monday the BBC ran a story in which its reporter chartered a light aircraft to fly over China's augmentation of reefs in the South China Sea's Spratly archipelago. The  intent was to see first hand what China has been up to and to gauge the kind of reaction the flight might prompt.

Predictably, the PLA Navy responded in a heavy handed way, and the story added wonderful texture to the ongoing coverage of the dispute. But unexpectedly, as the plane was heading home, the reporter heard an RAAF flight crew announcing to the PLA Navy a freedom of navigation exercise. The Australian Department of Defence has now confirmed, in general terms, that an RAAF Orion did undertake a 'routine maritime patrol', although not explicitly confirming the freedom of navigation exercise or the exact nature of the aircraft's flight.

Nonetheless it seems clear that rumours of an Australian response to China's island building activities, which have been doing the rounds in Canberra, are true. Indeed some believe that this was not the first flight and that the RAN has also been involved, though that remains unconfirmed.

At various points this year, Australia has publicly contemplated some kind of response beyond diplomatic statements. Then Defence Minister Kevin Andrews said in June that Australia should test China's resolve; commentators and analysts have made similar calls. Yet in public, the Australian Government has deliberately sought to hose down the heated rhetoric that has from time to time prevailed in debate about the South China Sea,  cleaving to what might be called the 'Carter formula', after the tone struck by US Defence Secretary Ashton Carter at the Shangri-La Dialogue this year.

The formula involves calls for all parties to stop construction, to halt militarisation of disputed features, to resolve disputes diplomatically and in accordance with prevailing international law, and emphasising that building features does not change how the US acts in the region. Carter famously stated that the US will 'fly, sail and operate wherever international law allows'. This formula has shaped formal public pronouncements such as the AUSMIN communique and statements at regional multilateral forums.

From the information we have so far, we can reasonably conclude that Australia is continuing to follow this approach to the issue, but has chosen to act on the final component of Carter's formulation.

But it has done so in a deliberately low key manner, in contrast to the US, which has been very public about its efforts, including by putting a CNN crew in a surveillance aircraft as well as the much publicised USS Lassen exercise (although the PR on that one was a complete mess). It appears Australia wanted to send a signal to China that it did not believe China's actions changed the circumstances governing how the ADF operates in the Sea, but it wanted to do so in a manner that would not heighten regional tensions and would contain damage to the bilateral relationship.

Although we lack operational detail, it seems reasonable to infer that the exercise was a typical freedom of navigation operation (FONOP), not provocative but not entirely peaceable, and not an unnecessary 'test of resolve' that would carry greater risk. It is notable that Australia acted separately from the US. No doubt the US was aware of what Australia was doing, but it seems Canberra was making clear that this was not a coordinated action, and that it was acting at its own behest because of its own perception of its interests.

The fact that Australia has undertaken a FONOP of this kind should not come as a surprise. It is in keeping with the tone and tenor of comments made by senior Australian officials and politicians over the past year in relation to China's actions. This in turn has been informed by the Abbott Government's focus on speaking clearly and plainly about Australia's strategic intent in Asia. Unusually, senior public servants have been a part of this, with DFAT Secretary Peter Varghese and Defence Secretary Dennis Richardson emphasising the extent to which China's behaviour in the South China Sea was destabilising. The outgoing head of the Prime Minister's Department, Michael Thawley, said Australia was in a long term struggle for influence in the region. Shortly after coming to office, Prime Minister Turnbull said China was 'pushing the envelope' in the South China Sea and that Australia needed to stand up for a rules-based international order. Put in that context, a considered but quiet FONOP seems to be precisely in keeping the ideas informing Australian policy.

One of the key reasons for not making the exercise public is to lower the diplomatic and political cost of the action. Now that it is the public domain, we will see how China responds. While this is difficult to predict, China did not make too much of the USS Lassen transit. But there is a distinct possibility that China might decide to use this incident as an excuse to push Australia. Over the past eight years or so, China has made a habit of seizing on events to test new Australian governments. It did so with Rudd in 2009 following a range of events including the 2009 Defence White Paper. It did so again with Julia Gillard in 2011 with the announcement of the US Marine Corps rotation through Darwin, and it did so with new Foreign Minister Julie Bishop in 2013 following her response to announcement of an Air Defence Identification Zone in the East China Sea.

This may be just the pretext Xi Jinping's China needs to test Malcolm Turnbull's new team. If so, it may test the PM's belief that there is no better time to be an Australian.