European nations are increasingly optimistic that they can support Ukraine financially and militarily against Russia even if President Trump decides to wash his hands of the conflict, as he often threatens, and instead focuses on normalizing relations with Moscow. But even with their best efforts, the Europeans cannot replace all of what the United States provides Ukraine — most important, real-time intelligence about Russian forces, incoming missiles and how and where to target the enemy. Ukraine’s ability to fight effectively relies largely on that American intelligence. “The Ukrainians don’t want this to be cut off no matter what,” said Camille...