Dr. Mathew Davies is Head of the International Relations Department at The Australian National University. He specializes in Southeast Asian politics. The opinions expressed in this commentary are solely those of the author.

(CNN) China is winning the battle over the South China Sea, the resource-rich stretch of contested water where the country's been building artificial islands equipped with military-length airstrips.

A clear example of this can be found in the Chairman's Statement released after the recent meeting of the Association of Southeast Asian Nations (ASEAN) leaders in Manila.

What's not clear is whether it's a sign of broader deal-making in Asia which may or may not relate to the current push by the US and China to rein in North Korea.

If so, it may mark a return to "old politics."

The ASEAN statement

This year's Chairman's Statement, a carefully negotiated compromise between the wishes of ASEAN's 10 member states, signaled a clear step back from some of the critical language the alliance used only a year earlier at the 29th Summit.

This time there were no mentions of ASEAN's serious concern over recent developments, no claim that trust was being eroded and no mention, at least in the part of the document concerned with the South China Sea, of the importance of the rule of law and the UN Convention on the Law of the Sea.

This victory is not just one of who occupies the most islands with the most military bases -- it is a victory of China's ability to control the agenda and have its "core interests" listened to and respected in discussions around the region.

The changing language in the ASEAN Chairman's Statement is more evidence that the big powers matter and the smaller powers must accommodate them. The South China Sea has been a "perfect storm" for the regional body, its own members divided and confronting Asia's most powerful state.

China's victory here is significant -- setting a new expectation for how ASEAN will deal with the issue and increasingly normalizing, at least in official documents, its position in the South China Sea as a step towards long-term occupation.

Just a coincidence?

There is, beyond the South China Sea, an interesting coincidence that suggests something bigger may also be going on in East Asia. The Chinese victory over ASEAN's statement comes at the same time as increasing US pressure on North Korea . Add to this that President Trump has also changed language on Chinese President Xi Jinping, recently praising him on making efforts to help address the North Korea issue.

If this is more than coincidence, and with President Trump we should always exercise caution in discerning a trend, then there is a grand bargain emerging -- concessions to China on the South China Sea in return for expectations of support on North Korea.

Behind this bargain, if it exists, would also be a return to a very old vision of international politics -- based less on the rule of law and more explicitly on the alignment of great power interests. This would be a big step away from the traditional US position and the expectations of US allies and friends in the region.

JUST WATCHED Trump and China: What's at stake? Replay More Videos ... MUST WATCH Trump and China: What's at stake? 01:26

Changing leaders

However, there are other reasons ASEAN has stepped back its pressure on China.

First, China has been more successful at influencing individual ASEAN member states than in the past. Traditionally Cambodia has been China's keenest defender inside ASEAN. Now, however, Philippine President Rodrigo Duterte who chaired the meeting, has led the Philippines away from alignment with the US position which traditionally has strongly rejected China's claims in the South China Sea.

The Philippines, before Duterte, had its own claims in the South China Sea -- most importantly winning a clear victory over China in 2016 at the International Tribunal for the Law of the Sea. Now Duterte has signaled little willingness to pursue this victory, prioritizing China's friendship.

Second, the US position has changed. The Obama administration has rejected China's approach to the South China Sea as incompatible with international law and had offered clear and vocal support for ASEAN members who shared that position.

Now, under a President Trump, the US has been muted in its defense of international law in the South China Sea. With the backstop that the US represents now removed, ASEAN members face a different calculus when making decisions about how far to push China. Criticizing Beijing, or insisting that ASEAN use more forceful language, is now more exposed than ever.

China hopes that the recent ASEAN meeting and its concluding Chairman's Statement marks a new direction forwards for regional recognition of its position. Whether this is true, or alternatively the statement is an isolated incident, will depend more on the US's actions over the next year than it will on ASEAN member states. Such is the fate of small powers.