China needs defensible borders and so do her smaller neighbours. The big will prevail over the little. China doesn't fear much from the Siberian Tundra, the Himalayan Massif or the jungle warlords but her opening east to the sea is crowded with competitors and enemies. That's the trade door out and the attack door in. A few miles of open sea was once a barrier but no longer. Advanced technological societies sit on her doorstep and their US ally sails up and down with deadly tools nearby. Only a few minutes of missile time buffer China. She needs a bigger security buffer.
So do her neighbours. Taiwan and Japan need that buffer and are entitled to it. So do South Korea and the Philippines and they are entitled to it. They can't all have what they want.
The one option that never goes away is war. If China can recover Taiwan peacefully, that will open the sea door. If China can buy Siberia or North Korea like the US bought Alaska, that will open sea doors.
(Title doesn't have to pass if the neighbour's policy becomes subordinate to Beijing's.)
If China gets control of the Indian seacoast of Burma, that will open sea doors.
America can protest but it is sitting pretty with the best protected borders of any great state on earth.
China won't stop growing and despite short term economic malaise, the work ethic, education and profit motivation of the Chinese assure them an even bigger place in the future. The high volume of trade China has with the US pretty much rules out a hot war. But that's not enough. The law of the sea will have to make an exception for the seaward face of the new Chinese empire. If China makes it worthwhile to Taiwan, North Korea, the Philippines, Siberia and the United States, war can be avoided but it may be painful for some. Unfortunately the Chinese leadership is motivated to blame foreign threats when corruption at home and an excess of young unmarried males are threatening political control.
The stakes were raised when China claimed the islands in the "China Sea". Now they are challenging the right of free passage to US ships. This is a scary episode. They ordered the American ship to stop. When it didn't, they parked a smaller naval vessel in the path of the Americans. (The American vessel, USS Cowpens was on a provocative mission shadowing the new Chinese carrier.)
For more educated background on this opening-to-the-sea argument, listen to Friedman and Kaplan of Stratfor.