BRADDOCK, Pennsylvania — The fate of the Edgar Thomson Works, a massive steel plant that has hugged the same spot along the Monongahela River since 1875, became even more uncertain Friday morning when President Joe Biden announced he would block the sale of U.S. Steel to Nippon Steel as one of his last acts as president.

Biden said he blocked the $14 billion takeover of U.S. Steel by Japan‘s Nippon Steel on the grounds the sale was a threat to national security.