I don't know so much about China, but I know that what nuclear weapons the North Koreans possess they possess because of the US breaking promises. And as for Japanese aggression, they have already claimed various islands. And whilst they may have no real "military" installations of their own, they certainly allow plenty of them to be built and maintained. In short, I agree that China and North Korea are acting increasingly aggressively, but I really don't think they are the ones responsible. All current problems seem to pretty much undeniably trace back to US - and other western - interference in the region: even the main reason for Japan's imperialistic foray into mainland East Asia was in response to European and American empire-building. So it seems to me that the only requirement for talking about Chinese and North Korean aggression is to first ignore past and current Japanese and Japanese-sanctioned aggression.