A withdrawal of military forces to lines set out in the first phase of a U.S.-brokered cease-fire deal between Israel and Hamas got underway within hours.

The Israeli military said Thursday that it has begun preparing to withdraw troops from Gaza after Hamas and Israel reached an agreement to end the two-year-old war.

The Israeli army began withdrawing its troops from Gaza on Friday under the first phase of a U.S.-brokered cease-fire agreement, marking what could be the...