The Israel Defense Forces said it was calling up to 6,000 troops for reinforcements along the border as leaflets were dropped urging Lebanese residents to leave their homes and move north of the Litani River 25 miles (40 kilometers) from the Israeli border.

We ask questions that might seem extraordinary if our families at home knew we were pondering them. Should we put CNN on top of the car? Does that make us less of a target — or more of one?

Also on Friday, two Israeli Apache attack helicopters crashed in northern Israel after colliding in midair, the Israel Defense Forces said. The pilot was killed and three others on board the copters were injured.