With a simple visit to an obscure factory on Monday, Chinese President Xi Jinping has raised the specter that China could potentially cut off supplies of critical materials needed by huge swaths of the U.S. economy, underscoring growing concerns that large-scale economic integration is boomeranging and becoming a geopolitical weapon. Keith Johnson and  Elias Groll write in Foreign Policy that Beijing could slam every corner of the American economy, from oil refineries to wind turbines to jet engines, by banning exports of crucial minerals.