Despite promised blowback from Europe, Donald Trump formally raised steel and aluminum tariffs to 50% from 25% on Tuesday. The move by the president raises trade tensions at a time when the US is locked in negotiations with numerous trading partners over his so-called “reciprocal” duties before a July 9 deadline.

Economic growth will slow this year and next as the trade war hampers development in the United States and around the world, the Organization for Economic Cooperation and Development said.