DEIR AL-BALAH, Gaza Strip — Israeli warplanes on Saturday struck parts of southern Gaza it had described as safe zones when telling Palestinians to evacuate, while displaced residents said the constant bombardment left many families without food and sleeping outside in the cold.

       Frustration was growing with the United States after it vetoed a United Nations Security Council resolution demanding an immediate humanitarian cease-fire, despite wide international support, and approved the emergency sale of tank ammunition worth more than $100 million to Israel.

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       Gaza residents “are being told to move like human pinballs — ricocheting between ever-smaller slivers of the south, without any of the basics for survival,” U.N. Secretary-General Antonio Guterres told the council before the vote.