.Biden preparing to block Nippon Steel purchase of united state Steel The Washington PostU.S. Steel claims it could possibly leave Pittsburgh if Nippon package flops as Biden intends to shut out takeover Pittsburgh Post-GazetteBiden Expected to Block USA Steel Requisition The New York TimesExclusive|United State Steel Portend Vegetation Closings if Sale Collapses The Exchange JournalBiden readied to block United States Steel purchase by Nippon Steel CNN.