China’s on-the-ground military influence, at present. (This is just a well-educated guess, of course. I am not a military analyst.)
Okinawa is the red dot. The red line is the objective reach of China’s military: the amount of space in which China can hold sway, without it becoming a big issue. One way to read this map is that the United States, with Japan, has planted its military power at China’s front door.
When China decides to be more aggressive, the map will look more like this:
Inevitably, the goal will be this:
If you are in Pennsylvania, you would not even notice this. It is your paying money into the U.S. treasury–a lot–for something like the top map, when, in fact, the bottom map (no U.S. presence) really is the same difference.
(P.S. you have to know which one is China, and which one is Japan. And where Taiwan and the Koreas are. Since you’re my readership, I know this is not a problem.)