We hear a lot about China's military these days, but perhaps that is mostly US spin. For Japan, they dominate the international news as well, but in fact, by far the most approaches to Japanese airspace are done not by China, but by Russia.
In any case, we can all hope nothing ever heats up over such things. Japan has an excellent self defense force to help deter aggression by its neighbors. Here they are in action. Note that the international language of aviation is English as spoken by the pilot in his radio communications in this video.
By the way, although the aircraft featured looks like a General Dynamics F-16 "Fighting Falcon", it is actually the larger Mitsubish F-2A "Viper-Zero" built in the 1990s - 60% by Mitsubishi and 40% by Lockheed Martin.