As Japan's ruling party moves to pick Prime Minister Shinzo Abe's successor, analysts in the United States are concerned Tokyo may see a return to an era of revolving-door leadership amid security challenges in Asia, even though they expect the U.S.-Japan alliance to remain robust.Japan's Chief Cabinet Secretary Yoshihide Suga is believed to be on course to win the Sept. 14 ruling party leadership race that will decide the next prime minister, casting himself as a candidate qualified to carry Abe's policy legacy forward after serving as the administration's public face over its nearly eight…READ FULL ARTICLE