JERUSALEM — Israel said its ground troops crossed into Lebanon overnight, launching what the military described as “localized” raids to root out Hezbollah fighters and infrastructure. Hezbollah, meanwhile, said it saw no sign of Israeli forces and its troops were ready to confront them.

Israel warned Lebanese people to evacuate border communities to avoid harm from limited ground operations it said were launched against Hezbollah, and said it would retaliate if Hezbollah ally Iran launched a missile attack on Israel that a senior U_S_ official said could come “imminently.