Tens of thousands of displaced and exhausted Palestinians have packed up their tents and other belongings and fled the southern city of Rafah for other parts of Gaza, according to the United Nations.

Israel has repeatedly threatened to invade Rafah, saying it’s the last stronghold of Hamas militants. Some 1.3 million Palestinians — over half Gaza’s population — had sought refuge in the city.

“Where are we supposed to go? Where is the world, that’s just watching us?” said Ahmad Abed, who has an 8-month-old daughter. “It’s like we’re sheep.”

Israeli Prime Minister Benjamin Netanyahu said Thursday that a U.S. threat to withhold some weapons would not deter Israel from expanding its offensive in Gaza. A limited Israeli operation earlier this week captured the Gaza side of Rafah’s border crossing with Egypt, throwing humanitarian operations into crisis.