People can say that China’s been escalating the situation all they want, but the facts are that realpolitik necessitates doing something. China needs to show ASEAN two things simultaneously:
Aligning with China is beneficial
Aligning with the US is harmful
(1) Is easy: China FDI outflows to ASEAN countries have been absurd, China is dumping money to connect Vietnam to China’s HSR network (at cost), improving Cambodia’s role in international trade through canal construction, obscene EV deals in Indonesia/Malaysia, and more.
(2) is much more difficult. Many ASEAN countries have been trying to thread the needle between taking Chinese money and accessing US markets. The Philippines is, obviously, the most egregious player here. China is trying to show ASEAN that aligning with the US has consequences (in contrast, Duterte’s Philippines had a very healthy relationship with China), especially as China looks to build a regional trade superbloc akin to NAFTA.