Thanks to Sam for linking to Ernie Bower's excellent piece on China and ASEAN in light of the Phnom Penh contretemps. He and others are right to see this as an important event, because it chillingly shows China's determination to get its own way over its smaller neighbours, and to be seen to do so. 

It feels as if regional power politics has crossed a threshold, but what exactly does it all signify? Three quick observations. 

First, we should not be too surprised that China does not much like ASEAN. It is not just about the South China Sea but about China's wider ambitions in Asia. Any great power that aims for regional leadership will always be somewhere between lukewarm and hostile towards an institution that promotes collective regional decision-making.

And not just China. For a long time, Washington was notably lukewarm towards ASEAN's ambitions for a wider regional role, for the simple reason that ASEAN's model of collective and consultative regional leadership was incompatible with America's view of its own leadership role in Asia. 

Indeed one could argue that America only became enthusiastic about ASEAN's wider role in Asia when it started to worry about China's challenge to its own regional leadership. Likewise, Beijing promoted ASEAN's role when ASEAN has offered ways to promote China's position in Asia at America's expense, as the ASEAN+3 initiative did. Now Beijing sees it differently.

Second, ASEAN's problem in Phnom Penh was no passing diplomatic squall. It reflects a deep shift in ASEAN's environment.

I suspect ASEAN has only worked as well as it has for the last four decades because Asia has been free of serious great-power strategic rivalry almost since it was founded. ASEAN solidarity has not had to battle against the efforts of competing great powers to create spheres of influence.

Now, after forty years, great-power rivalry is again emerging as the major strategic force in the region, and ASEAN is caught in the crossfire. Washington is trying to use ASEAN to erode Beijing's influence in Asia by exacerbating China's self-inflicted problems with its Southeast Asian neighbours.  Beijing is pushing back: the real target of it ruthless diplomacy in Phnom Penh was not the Philippines but America. 

Third, we should not be too optimistic that ASEAN solidarity will withstand the pressure from Beijing and Washington. Many people hope and expect that ASEAN will bounce back from Phnom Penh and reassert its cohesion in the face of outside pressure. Maybe, but in the long run it will be very hard for ASEAN to preserve a united front against China. The raw facts of geography mean that different ASEAN members have very different interests in relation to China, and all of them have too much at stake to sacrifice their interests to support others. In the end, Indonesia will not risk its relationship with China to support Vietnam over the Spratlys.