President Trump announced that he would be doubling tariffs on steel to 50% as he visited a U.S. Steel mill in the Pittsburgh suburbs Friday, a week after teasing a "planned partnership" between the company and its Japanese competitor Nippon Steel.

By Sayantani Ghosh, David Gaffen, Arpan Varghese SAN FRANCISCO/NEW YORK/BENGALURU (Reuters) -President Donald Trump's trade war has cost companies more than $34 billion in lost sales and higher costs,