.Biden preparing to block Nippon Steel acquisition of U.S. Steel The Washington PostU.S. Steel claims it could leave Pittsburgh if Nippon deal falls through as Biden prepares to block requisition Pittsburgh Post-GazetteBiden Expected to Block USA Steel Requisition The New York City TimesExclusive|U.S. Steel Warns of Plant Closings if Sale Falls Down The Commercial JournalBiden prepared to block out United States Steel purchase by Nippon Steel CNN.