Separately Tuesday, Lu warned foreign countries against "interfering with China's internal affairs" after the U.S. Embassy in Beijing called for the release of Liu Xiaobo, a democracy activist and Nobel Peace Prize laureate who was diagnosed with terminal liver cancer after eight years in prison. Since his inauguration, President Donald Trump has generally taken a conciliatory tone toward Beijing on a range of issues including trade and currency while courting President Xi Jinping's cooperation in exerting pressure against North Korea's nuclear program.