U.S. President Donald Trump has postponed a decision on imposing steel and aluminum tariffs on Canada, the European Union and Mexico until June 1, and has reached an agreement in principle with Argentina, Australia and Brazil, a source familiar with the decision said on Monday. The decision came just hours before temporary exemptions were set to expire at 12:01 a.m. (0401 GMT) on Tuesday. “The administration has reached agreements in principle with Argentina, Australia, and Brazil, details of which will be finalized in the next 30 days. The administration is also extending negotiations with Canada, Mexico, and the European Union for a final 30 days,” the source said. Trump imposed a 25 percent tariff on steel imports and a 10 percent tariff on aluminum in March, but granted temporary exemptions to Canada, Mexico, Brazil, the European Union, Australia and Argentina. He also granted a permanent exemption on steel tariffs to …