President Trump unveiled the higher duties at a rally on May 30 promoting a $14 billion deal between Japan’s Nippon Steel and U.S. Steel which he said would ensure U.S. control over the company. Trump said that the move to increase the levies, which took effect June 4, would bolster the domestic industry and protect U.S. jobs. Cleveland-Cliffs shares surged 23% on Monday, while Steel Dynamics and Nucor shares each gained 10%.