BEIJING (AP) — Japanese stocks tumbled while Chinese markets gained Monday after Donald Trump took office as U.S. president and promised "American first" policies, adding to concerns about the threat of protectionism. Trump has rattled businesspeople in Japan, China and other major U.S. trading partners who worry about his promises to restrict commerce and shift jobs back to the United States. ANALYST'S TAKE: "Trump's inauguration speech really offered nothing new for investors to latch on, besides harping on old themes of economic 'carnage' that will be stopped," said Mizuho Bank in a report. A crop of encouraging company earnings news helped lift the market. Benchmark U.S.