.Biden prepping to block Nippon Steel purchase of united state Steel The Washington PostU.S. Steel mentions it might leave Pittsburgh if Nippon offer falls through as Biden intends to shut out requisition Pittsburgh Post-GazetteBiden Expected to Block U.S. Steel Takeover The New York TimesExclusive|USA Steel Portend Plant Closings if Purchase Collapses The Exchange JournalBiden prepped to block US Steel purchase through Nippon Steel CNN.