"Hamas bears total responsibility for the war, and for the resumption of hostilities," a State Department spokesperson said.

"Every death would have and could have been avoided had Hamas accepted the 'bridge' proposal that SE Witkoff offered last Wednesday."

It was a reference to ideas from Witkoff, a friend of President Donald Trump, to ease Israel and Hamas toward extending a ceasefire.

Israel said it had no choice but to resume fighting to free remaining hostages seized on October 7, 2023. The Hamas-run health ministry in Gaza said that more than 400 people died.

"Hamas is delaying the compelling deal in front of us and forcing Palestinians to suffer the consequences," the State Department spokesperson said.

National Security Council spokesman Brian Hughes said earlier: "Hamas could have released hostages to extend the ceasefire but instead chose refusal and war."

The Trump administration has staunchly backed Israel, whose resumed military operations drew condemnation from most world capitals which reacted.