Seoul, South Korea CNN — It’s an arms race bigger than anything Asia has ever seen – three major nuclear powers and one fast-developing one, the world’s three biggest economies and decades-old alliances all vying for an edge in some of the world’s most contested land and sea areas. In one corner are the United States and its allies Japan and South Korea. In another corner, China and its partner Russia. And in a third, North Korea. With each wanting to be one step ahead of the others, all are caught in a vicious circle that is spinning out of…