Other countries in the South China sea are mostly weak too, other than Japan. The big factor is the United States, due to its treaty relations with other countries in the area like Philippines, Japan and Taiwan. But you know that.

I'm calling it experimental because they seem to be exploring their options rather than seeking head-on confrontation in the manner of Putin - I get the sense that China is not sure of its strategic position and is probing to see whether it could establish a 'new normal' without actual conflict. But that's just a hunch on my part, I have no special insight.