Washington (AFP) – Joe Biden leaves Thursday for his first trip as president to Asia convinced that the confrontation with Russia has reinvigorated US leadership, while wary that a rogue North Korean nuclear test could tear up the optimistic script. The Democrat is going to South Korea, then Japan on Sunday to hold summits with the leaders of both countries, as well as joining a regional summit of the Quad group — Australia, India, Japan, and the United States — while in Tokyo. During the first leg, he will visit US and South Korean troops, but will not make the traditional presidential trek…