Actually, China has a claim to both the Paracels and the Spratleys.
China’s isn’t the only claim, but her claim is a lot better than that of Malaysia, Brunei, etc.
Now that she has a sea-lift ability, what else is to be expected than that she would try and enforce those claims?
It’s only a “crisis” if China finds the going so easy that she comes to think she can expand even beyond her “natural waters”; and not stop until she fines resistance.
(But will she find any real “resistance”?)
Is the Phillipines (which has, IIRC, one ex-US Coast Guard vessel for a navy) expected to resist?
Several of these countries had pressed their claims in the past with the comfort of knowing the US was in the area and would back them up. Now that the US has less of a pressence — in part because countries like the Phillipines kicked us out in a fit of hubris and nationalism — they are left to face China alone. So the chances of them winning any of these claims are pretty slim. So, of course, now countries like the Phillipines are screaming for us to back them up again. As ye sew, so shall ye reap.