Chancellor Angela Merkel visits China on Thursday, seeking to close ranks with the world’s biggest exporting nation as US President Donald Trump shakes up explosive issues from trade to Iran’s nuclear deal. Finding a common strategy to ward off a trade war and keep markets open will be Merkel’s priority when she meets with President Xi Jinping, as Washington brandishes the threat of imposing punitive tariffs on aluminium and steel imports. “Both countries are in agreement that open markets and rules-based world trade are necessary. That’s the main focus of this trip,” Merkel’s spokeswoman Martina Fietz said in Berlin on...