President Trump threatened to drastically ramp up U.S. tariffs on Chinese imports, an 11th-hour twist that puts in doubt whether the two sides can reach a trade deal this week. In a pair of Twitter messages Sunday, Mr. Trump said he planned to raise levies on $200 billion in Chinese imports to 25% starting Friday, from 10% currently. He also said he would impose 25% tariffs “shortly” on $325 billion in Chinese goods that haven’t yet been taxed. …