Just days after reaching a truce with China, the US is preparing for another possible trade war, this time with the European Union. Washington has threatened to impose tariffs on European exports worth billions of dollars. It's part of a long-running dispute over the world's two leading planemakers. Paolo Montecillo reports. For more, we got expert analysis from Rajneesh Narula, a professor of international business regulation at the University of Reading’s Henley Business School.