China fired a warning shot at President Trump on Monday. Pushing back against Trump's desire to impose tariffs on roughly $50 billion of Chinese exports, China placed tariffs of its own on roughly $3 billion of American imports. Stock markets plummeted in part on the news, with the Dow Jones Industrial Average falling over 450 points, or 1.9 percent, and the S&P 500 falling over 58 points, or 2.2 percent.