President Emmanuel Macron is updating France's nuclear deterrence doctrine as Europe worries about Russia and doubts U.S. protection under Donald Trump. On Monday, Macron will speak at a French submarine base and signal how France thinks about using nuclear weapons. The war in Ukraine and Russia's nuclear threats have shaken Europe's security assumptions. Analysts say some Europeans are looking to France for a backup nuclear guarantee. France is the only nuclear power in the European Union. Macron last laid down policy in 2020 and said France has fewer than 300 warheads. Experts are listening for any stronger promise to protect allies.