Washington, 4 April

President Joe Biden issued a stark warning to Israeli Prime Minister Benjamin Netanyahu on Thursday that future US support for Israel's Gaza war depends on the swift implementation of new steps to protect civilians and aid workers.

Biden and Netanyahu 's roughly 30-minute call just days after Israeli airstrikes killed seven food aid workers in Gaza added a new layer of complication to the leaders' increasingly strained relationship.

Biden's message marks a sharp change in his administration's steadfast support for Israel's war efforts, with the US leader for the first time threatening to rethink his backing if Israel doesn't change its tactics and allow much more humanitarian aid into Gaza.

The White House would not specify what could change about US policy, but it could include altering military sales to Israel and America's diplomatic backup on the world stage. Administration officials said they expected the Israelis to make announcements on next steps within hours or days and that the US would then assess whether the Israeli moves go far enough.

Biden "made clear the need for Israel to announce and implement a series of specific, concrete, and measurable steps to address civilian harm, humanitarian suffering, and the safety of aid workers,” the White House said in a statement following the leaders' call. “He made clear that US policy with respect to Gaza will be determined by our assessment of Israel's immediate action on these steps.”

Biden also told Netanyahu that an “immediate cease-fire is essential” and urged Israel to reach such an accord "without delay," according to the White House.

The leaders' conversation comes as the World Central Kitchen, founded by restauranteur José Andrés to provide immediate food relief to disaster-stricken areas, called for an independent investigation into the Israeli strikes that killed the group's staff members, including an American citizen.

The White House has said the US has no plans to conduct its own investigation even as it called on Israel to do more to prevent the harming of innocent civilians and aid workers as it carries out its operations in Gaza.

Separately, Secretary of State Antony Blinken told reporters in Brussels that US support would be curtailed if Israel doesn't make significant adjustments to how it's carrying out the war. “If we don't see the changes that we need to see, there will be changes in our policy,” he said.

White House national security spokesman John Kirby echoed the call for “tangible” and “concrete” changes to be taken by the Israelis beyond reiterating long stated calls for allowing additional aid to get into Gaza. “If there's no changes to their policy in their approaches, then there's going to have to be changes to ours,” Kirby said. “There are things that need to be done. There are too many civilians being killed.”

The demands for Israel to bring the conflict to a swift close were increasing across the political spectrum, with former President Donald Trump, the Republicans' presumptive nominee to face Biden this fall, saying Thursday that Israel was “absolutely losing the PR war” and calling for a resolution to the bloodshed.

“Get it over with and let's get back to peace and stop killing people. And that's a very simple statement,” Trump told conservative radio host Hugh Hewitt. “They have to get it done. Get it over with and get it over with fast because we have to -- you have to get back to normalcy and peace.”