.Biden readying to block Nippon Steel investment of U.S. Steel The Washington PostU.S. Steel claims it might leave behind Pittsburgh if Nippon deal fails as Biden plans to shut out requisition Pittsburgh Post-GazetteBiden Expected to Block U.S. Steel Takeover The Nyc TimesExclusive|U.S. Steel Warns of Vegetation Closings if Sale Breaks Down The Exchange JournalBiden prepared to obstruct US Steel investment by Nippon Steel CNN.