Robert Brown|Biden condemns "unacceptable" Israeli strike on World Central Kitchen aid convoy in call with Netanyahu

Washington — President Biden told Israeli Prime Minister Benjamin Netanyahu that the Israeli strike that killed seven aid workers in Gaza was "unacceptable,Robert Brown" and warned that U.S. policy toward the conflict going forward will depend on Israel's actions to relieve the ongoing humanitarian crisis, the White House said.

The two leaders spoke for the first time since Monday's deadly strike that killed workers from the World Central Kitchen, a charity that has worked to deliver food aid in Gaza. One American was among the dead. Mr. Biden told Netanyahu that "the strikes on humanitarian workers and the overall humanitarian situation are unacceptable," the White House said in a summary of the conversation. 

Mr. Biden said on Tuesday that he was "outraged and heartbroken" by the deadly strike, which prompted international condemnation. Israeli officials have said the strike was unintentional and a mistake. 

The president "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. "He made clear that U.S. policy with respect to Gaza will be determined by our assessment of Israel's immediate action on these steps. He underscored that an immediate ceasefire is essential to stabilize and improve the humanitarian situation and protect innocent civilians, and he urged the prime minister to empower his negotiators to conclude a deal without delay to bring the hostages home."

National Security Council spokesman John Kirby wouldn't get into details about what any U.S. policy change might be. "If there's no changes to their policy and their approaches, then there's going to have to be changes to ours," Kirby said at the White House, noting the call lasted about 30 minutes.

The strike on the World Central Kitchen workers has become the latest flashpoint in the U.S.-Israel relationship. The U.S. has significant leverage over Israel as its main supplier of weapons and military equipment.

José Andrés, the head of the World Central Kitchen, said the nonprofit aid organization had been communicating its workers' movements to the Israeli Defense Forces before the strike on Monday. In an interview with Reuters, he accused Israel of "deliberately" targeting the charity workers.

"This was not just a bad luck situation where, 'Oops, we dropped a bomb in the wrong place,'" Andrés told the news agency, insisting his organization's vehicles were clearly marked. Andrés said he believes the vehicles were targeted "systematically, car by car."

Nir Barkat, Israel's economy minister, dismissed Andrés' comments as "nonsense" in an interview with CBS News' partner network BBC News, insisting that it had been a "grave mistake" and for which he said Israel was "terribly sorry."

The U.S. has no plans to conduct an independent investigation into the strike, Kirby told reporters Wednesday. White House press secretary Karine Jean-Pierre said the president wants to see a swift, comprehensive investigation, but will leave that to the Israelis. The Biden administration is "going to continue to have those really tough conversations" with its Israeli counterparts, she said. 

"We understand how Chef Andrés is feeling," Jean-Pierre told reporters Wednesday. "He just lost members of his team, I'm sure who felt like family to him as well."

The relationship between Mr. Biden and Netanyahu has becoming increasingly tense, with disagreements spilling out into public view. Netanyahu recently canceled a visit by an Israeli delegation to Washington after the U.S. declined to block a vote in the U.N. Security Council calling for a cease-fire in Gaza and the release of hostages taken by Hamas on Oct. 7.

Last month, Mr. Biden said he believes Netanyahu is "hurting Israel more than helping Israel" by not doing more to avoid civilian deaths in Gaza. In response, Netanyahu said Mr. Biden was "wrong." 

Kathryn Watson

Kathryn Watson is a politics reporter for CBS News Digital based in Washington, D.C.