Secretary of State Hillary Clinton headed for a global security conference in Germany on Friday as U.S. planners struggle to assess how Egypt's political crisis may rewrite both the future of the Middle East and the deadlocked Israeli-Palestinian peace process. Clinton will meet her European Union counterpart Catherine Ashton and other world leaders at the Munich conference, where she is also due to finalize the new U.S.-Russia nuclear arms pact with Russian Foreign Minister Sergei Lavrov. She is also due to lead the U.S. team at a meeting on Saturday of the "Quartet" of Middle East peace mediators, which includes the EU, Russia and the United Nations. The meeting, originally planned to discuss how to nudge Israel and the Palestinians back to peace talks, looks certain now to be dominated by the mounting revolt against Egyptian President Hosni Mubarak, who for 30 years has been a key U.S. ally and a central player in Middle East peace efforts. Egypt was the first Arab country to sign a peace agreement with Israel, and Mubarak still plays a constructive role, U.S. officials say. Many in Washington and Jerusalem fear that any government that succeeds Mubarak's may follow a radical Islamist line, which could hugely complicate U.S. efforts in the region.