WASHINGTON—President Donald Trump threatened a major escalation in trade tensions with Beijing on Thursday, saying he was considering imposing tariffs on an additional $100 billion in imports from China. The move would triple the amount of Chinese goods facing levies when entering the U.S., up from the tariffs on $50 billion in imports from China that the president announced last week. Mr. Trump, who justified the tariffs on Chinese imports by citing alleged violations of U.S. intellectual property laws, said Thursday that an escalation would be due to Beijing’s “unfair retaliation,” which could “harm our farmers and manufacturers.” Mr. Trump also said he would instruct the Agriculture Secretary to put together a plan “to protect our farmers and agricultural interests,” but he provided no details. After the U.S. threatened tariffs on Tuesday, China quickly came up with its own $50 billion hit list of U.S. exports to China, […]