The Israeli prime minister rejects calls for a cease-fire to facilitate the release of captives or end the war, which he has said will be long and difficult.

Frequent explosions from airstrikes lit up the sky over Gaza City after nightfall Friday, when an Israeli blackout of internet, cellular and landline services hit.

Officials said that the more than 600,000 Americans living in Israel and Lebanon are of particular concern, but they stressed that an operation of such magnitude is a worst-case scenario.