Block the sealanes by controlling the Spratlys Islands and then you have to route around a wide distance, but it goes beyond this....since China is also trying to control other islands that would allow it to stop shipping to the east of the Philippines.
China is claiming the Senakaku islands because they lie on the TGT line, between Okinawa and Taiwan. If they can take that, they can move around the south of Okinawa to mine and blockade Japan. In preparation for that they have created the largest mine warfare force in the world.
mainly bookmarked for later reading, but this is the reason PNoy compared China's moves to Hitlers. Today the papers are extolling friendship and that China will negotiate. Huh? They are digging up reefs and putting military onto areas where they have had no Chinese presence for hundreds of years except for a few fishermen and the Chinese pirates.
Yet they keep pushing the same meme, and figure no one will bother to stop them.
Because the Philippines is important for its location , in any conflict it will be ravaged and the casualties to its population will be immense. For most of the Pacific century the Philippines has been, like Poland, in the dubious position of being in the way of great powers going both ways. If the Pax Americana collapses, the Philippines will, as it did on December, 1941, be the first to know.