The challenge for US Defense Secretary Ashton Carter at the 15th Shangri-la Dialogue (SLD) this year was to deliver an address sufficiently convincing on US security commitment to the region that it would reassure Washington's allies and partners, without appearing unduly to raise the temperature of relations with China. This despite tensions over Beijing's actions in the South China Sea that have simmered almost continuously since last year's event.

PLA Deputy Chief  General Staff Adm. Sun Jianguo and US Defense Secretary Ash Carter in Singapore (Photo courtesy of Flickr)

That is seemingly the perennial challenge for US policy in the Asia Pacific. However, compounding the challenge for what may be Carter's last address to the Singapore-hosted security gathering, there was no new security initiative to announce this time, unsurprisingly, at the tail end of Barack Obama's presidency.

Instead, Carter's pitch in Singapore was loftier and more rhetorical, identifying 'commitment, strength and inclusion' as core precepts for the US approach to the region. The speech drew extensively from his recent remarks at the US Naval Academy, in Annapolis. Like last year, however, Carter chose to deliver harder-edged messages about Chinese behaviour, upfront, on US territory in the lead-up to SLD.

As the last SecDef's SLD address of Obama's presidency, this was also an attempt to distill and revalidate the US 'rebalance' to Asia. As in previous years, there was a predictable emphasis on affirming the durability and importance of the US security presence, which Carter claimed provides 'the region's oxygen', borrowing Joseph Nye's often-cited metaphor from The Paradox of American Power.

The address repeatedly drummed home the notion that a 'principled security network' exists in Asia undergirded by America's security partnerships, while also weighting the economic dimension to US  statecraft, including the still unratified Trans Pacific Partnership (TPP). The key messages are that US influence is benign, its core interests widely are shared in the region, and its networking power is a force for deepening cooperation — bilateral, trilateral, and multilateral.

Among the expected roll-call of treaty allies, Japan and Australia were mentioned first. Carter singled out freedom of navigation and overflight across the region as one area where the US and Australia 'work together', though this might be equally be read as an encouragement to do more. Mention of South Korea was scant by comparison, though Carter heralded an improvement in Korea-Japan inter-alliance ties. Also, Carter's claim that America's alliance with the Philippines 'is as close as it has been in decades', true under Aquino, must now contend with the wild card of a Duterte presidency. India, Vietnam and Singapore were singled out as flourishing US defence partnerships.

Carter's speech notably did not call out Chinese behaviour in specific terms. Nor was there any repeat call this year to reverse course on island-building and militarisation. This left some delegates wondering if the US was in fact backing down. Carter recycled a rhetorical assertion from his Annapolis speech that Beijing's actions in the South China Sea 'could end up erecting a Great Wall of self-isolation'. Carter's assumed aim at SLD was to invite a qualitative comparison between an American brand of 'principled' engagement and Chinese actions that threat to 'undercut' shared principles. China's pushy nationalism has certainly alienated many countries in Asia. But it would be wrong to characterise China as isolated.

Ash Carter was conspicuously the only US official to speak at SLD this year. Admiral Harry Harris, PACOM's normally outspoken commander, was seen but not heard, substantiating earlier reports of a 'gag order' put in place by a White House, no doubt anxious to maintain communications discipline ahead of high-level US-China talks currently underway in Beijing.

Even Senator John McCain delivered his speech at a separate location in Singapore, inter alia giving his blessing for TPP ratification but disappointing many in the region by failing to mention the UN Convention on the Law of the Sea as part of the 'rules-based order'.

While Carter's was the lone US policy voice at this year's SLD, the presence of a lofty US delegation, including the Chief of Naval Operations, indicates there was plenty going on in the margins. One frustration, even as an SLD delegate, is knowing that while media attention focuses on the increasingly ritualised US-China set piece, the most significant interactions occur at roped-off sections of the hotel. Asia's biggest gathering of defence ministers and top brass functions in tandem as a sort of uniform-themed speed-dating jamboree.

As in 2015, China's delegation was again headed by Admiral Sun Jianguo, who appears to have warmed to a role he did not originally want. Sun's plenary speech, delivered a full day after Carter's, pushed back predictably on the allegation of self-isolation. His counter-emphasis on China's 'inclusive, shared, win-win' regional vision (think One Belt, One Road instead of TPP) reveals a mirror-imaging dynamic at play, as the US and China present dueling versions of inclusiveness for an Asian audience, whose bottom-line interest is for everyone to just get along. That hope looks increasingly forlorn.

The harder hitting half of Sun's address included harsh words on US plans to field its THAAD missile defence system in South Korea. The Philippines was also singled out for stinging criticism, including a pre-emptive dismissal of the upcoming tribunal ruling from the Permanent Court of Arbitration.

Given CCTV's coverage of SLD this year, it is possible that Sun's primary target audience was in China itself, but the shrill tone is unlikely to go down as well elsewhere in the region. In fact, Singapore's eloquent Defence Minister Ng Eng Hen later went out of his way to question Admiral Sun's 'puzzling' and 'somewhat surprising' claim that the regional security architecture is 'not inclusive', given ASEAN's ecumenical embrace of security engagement, including recent 'plus one' activities with China. For those present in the ballroom, Sun's bellowed address will be remembered simply as the loudest in Shangri-la history.

One unfortunately silent voice was Australia, not represented at SLD by a minister for the first time in fifteen years. While an election campaign is ongoing, this was certainly a missed opportunity, since it has been an eventful year in Australia's defence policy, and the SLD offered a prominent platform for Defence Minister Marise Payne to major on Australia's most important Defence White Paper in years.

Her absence only serves to confirm the limited bandwidth allocated to external issues in the election. Let's hope that Ash Carter's appeal for 'forward-thinking statesmen and leaders' to attend such events as SLD registers in Canberra, ensuring that Australia is represented at an appropriate level next year.