President Trump pressed ahead with import tariffs of 25 percent on steel and 10 percent for aluminum but exempted Canada and Mexico and offered the possibility of excluding other allies. Trump said in a White House announcement that the best outcome would be for companies to move their smelters and mills to the United States, adding that domestic metals production was vital to national security. Plans for the tariffs, scheduled to begin in two weeks, have stirred opposition from business leaders and even some prominent members of the Republican Party. Critics are concerned the duties could spark retaliation from other nations and hurt America's economy.