East Asia belongs among the main economic and technological axes of the present globalized world. With the growth of Chinese assertiveness, presence of North Korean regime, and diffusion of modern technologies there emerge contemporary security challenges of global implications. The main aim is to introduce the given questions in a nutshell, and in context of selected issues following the San Francisco System and the Sino-Japanese competition for regional hegemony. A partial objective is to point out eventual implications also for the European security space.