It’s hard to know if Trump's comments on Xi Jinping suggest the world’s two biggest economies are getting any closer to a deal on tariffs.

President Trump went after Xi Jinping on social media as China's commerce ministry went to the World Trade Organization in response to unilateral tariffs.

U.S. President Donald Trump called China's Xi Jinping tough and "extremely hard to make a deal with" on Wednesday, exposing frictions after the White House raised expectations for a long-awaited phone call between the two leaders this week.