The mood among staff in the State Department is worse than during the disastrous US invasion of Iraq, according to a former staffer, as the fallout from the killing of .

Secretary of state Antony Blinken responded to an initial flurry of dissent cables over the war in Gaza back in November, writing in a letter to staff to acknowledge the sentiment.

“I know that for many of you, the suffering caused by this crisis is taking a profound personal toll,” Mr Blinken said in the letter obtained by Reuters.

Palestinian children play amongst the rubble in Rafah (AFP)

Palestinian children play amongst the rubble in Rafah (AFP)

“The anguish that comes with seeing the daily images of babies, children, elderly people, women, and other civilians suffering in this crisis is wrenching. I feel it myself,” he said.

Mr Blaha, who retired last year, said he had been asked by several people whether he would have resigned if he was still in his post.

“My only answer has been, I’m really glad I’m not in that position,” he said.

Mr Biden told prime minister Benjamin Netanyahu on Thursday that future US policy towards Israel will be determined by whether its government takes action to protect aid workers and civilians in Gaza.

The warning came in their first telephone conversation since Israel Defense Force drones fired three missiles into a World Central Kitchen aid convoy.

In a readout of the call, the White House said Mr Biden told the Israeli leader that the strike on aid workers and the “overall humanitarian situation” in Gaza were both “unacceptable” and “made clear” to Mr Netanyahu that US policy will hinge on whether his government can “announce and implement a series of specific, concrete, and measurable steps to address civilian harm, humanitarian suffering, and the safety of aid workers”.

The Israeli army announced on Friday that its internal investigation into the incident had concluded.

While admitting that a “grave mistake” was made, the Israeli military continued to claim innocence over the attack – insisting that the WCK workers were “misidentified” as Hamas militants. Two military officers have been dismissed from their positions following the findings, the military said.