Mattis' trip to Japan and South Korea, the United States' most important allies in Asia, is meant to reaffirm Washington's commitment to the countries at a time of growing regional uncertainty . China's economic rise and quick progress in turning its wealth into military power have set off a new round of competition in the South and East China seas. And in the process, Beijing has upset the strategic order that has prevailed in East Asia since the end of the Cold War. Though Trump has yet to lay out his foreign policy strategy toward China, recent comments from the president and his staff suggest that the administration considers China a major threat to U.S. interests in Asia and around the world.