A man tries a mobile phone made in China at a Best Buy store in New York, the United States, on March 22, 2018. Despite strong warnings from business groups and trade experts, U.S. President Donald Trump on Thursday signed a memorandum that could impose tariffs on up to 60 billion U.S. dollars of imports from China, the latest unilateral move that poses a threat to global trade. (Xinhua/Wang Ying)