By James Mackenzie, Jana Choukeir and Maha El Dahan JERUSALEM/DUBAI (Reuters) -Israel's military has called up reservists in preparation for a possible resumption of fighting in Gaza if Hamas fails to meet a Saturday deadline to release more Israeli hostages and a nearly month-old ceasefire breaks down.

Their worries are exacerbated by President Donald Trump’s demand that all of the hostages be freed by Saturday — and his insistence that Gaza be emptied of all Palestinians and redeveloped as a tourist enclave.

Famine has been mostly averted in Gaza as a surge of aid enters the territory during a fragile ceasefire, the United Nations humanitarian chief said Sunday. But he warned the threat could return quickly if the truce collapses.