They (China) are doing this to counter US presence in around the region. In my opinion, however, I do not think that they will strike any ASEAN countries, that would result in unwanted global response to their image. They have already sent a battle group into the IOR (Indian Ocean Region) to press their interests there.
They have aided Pakistan build a naval port in Gwadar, as well as courting Sri Lanka's government to build a port on their coast. The Chinese, unlike what media is reporting, is placing more emphasis not on East Asia or South East Asia, but in the IOR and abroad. In particular her interests in Africa, in which she has multi-billion dollar infrasctructural investment projects.
They know that any military provocations in SEA / WPS will result in unwanted American response; to which China does not have the resources to counter at the present moment. In 2 decades, however, when their naval power is expected to ecclipse that of the United States,...it will be more "open game".
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