The first one above shows Chinese maritime claims. The Spratly islands have been a major source of contention in the region because virtually every South East Asian nation has lain some sort of claim on what many believe is a oil rich region of the world. As you can see in the graphics below the nations of South East Asia are being very aggressive in their claims.
I also wrote in my post that China is in a very undesirable position when it comes to the sea lines. As you can see in the illustration the limitations of Chinese submarines operations below, there are many choke points and few avenues of exit for the Chinese. If a conflict did break out between the United States then China would spend much of its time, and resources, figuring a way to break out the box that geography has placed them in.