US President Joe Biden and Israel Prime Minister Benjamin Netanyahu

WASHINGTON — President Joe Biden issued an ultimatum to Israel that U.S. support in the Gaza war depends on “immediate” steps to protect civilians and aid workers, the White House said Thursday.

Within hours of a tense call between Biden and Israeli Prime Minister Benjamin Netanyahu, the Israeli government said it would take new measures to increase aid to the devastated coastal enclave, including opening the Erez crossing from Israel into northern Gaza and the Ashdod port, and increasing aid deliveries from Jordan.

It was unclear if those steps would satisfy Biden. A National Security Council spokeswoman said Thursday night the steps “must now be fully and rapidly implemented.”

“As the president said today on the call, U.S. policy with respect to Gaza will be determined by our assessment of Israel’s immediate action on these and other steps, including steps to protect innocent civilians and the safety of aid workers,” spokeswoman Adrienne Watson said.

Biden spoke with Netanyahu three days after a team from celebrity chef José Andrés’ World Central Kitchen aid group were killed in an Israeli drone strike in northern Gaza.

“President Biden emphasized that the strikes on humanitarian workers and the overall humanitarian situation are unacceptable,” the White House said in a statement earlier Thursday. “He 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.”

Biden “made clear that U.S. policy with respect to Gaza will be determined by our assessment of Israel’s immediate action on these steps,” the statement said. On Friday, the Israeli military said it had fired two officers and reprimanded others for the World Central Kitchen drone strike.

Veteran U.S. diplomat Dennis Ross, now at the Washington Institute for Near East Policy, said Biden had given Netanyahu a clear ultimatum. “The president, in effect, is saying meet these humanitarian needs or I will have no choice but to condition (military) assistance,” Ross said.

Monday’s drone strike on the World Central Kitchen team marked the first time foreign aid workers, including one American citizen, have been killed in the six-month Israel-Hamas war, prompting a swift apology from Netanyahu and the Israeli military, and a condolence phone call by Biden to Andrés.

The deaths of foreign humanitarians, coupled with Andrés’ celebrity status and popularity in Washington, appears to have shaken Biden administration at a time when surveys show that a majority of Americans no longer support Israel’s war against Hamas.