“The U.S. asked for an explanation of the first [attack] on Jabalia,” said the official, adding that the conversation was in the context of “asking Israel to do more to avoid civilian casualties.”

From the beginning of the conflict, the U.S. has asked questions of Israel about their goals and how to achieve them, and urged them to avoid harming civilians, the official stressed. However, U.S. “support for Israel’s right to defend itself remains solid.”

Pentagon officials have asked the Israel Defense Forces specifically about the Israeli bombardment of the Jabalia Refugee Camp in northern Gaza on Tuesday, an Israeli official said, adding that Israel “puts a lot of effort into ensuring civilians are out of harm’s way.”

More than 9,000 Palestinians have been killed since Israel responded to Hamas’ Oct. 7 attack, per the Hamas-led Gaza Health Ministry, nearly 4,000 of them children. Experts say Israel’s tolerance for civilian casualties seems to be far higher than that of the United States.

A House Democrat familiar with U.S.-Israeli conversations said the administration “has been pushing very hard in private on the Israelis to ease back” — particularly after the bombing of the refugee camp.

The House member added Democrats are preliminarily discussing measures to penalize Israel should it not change course, such as “actual enforcement of existing human rights vetting.”

“There are mechanisms in place to achieve what we need to achieve,” the lawmaker said, like the Leahy Law that prohibits assistance to countries committing human rights abuses.

“Whenever we provide military assistance to partners including Israel … we do make clear that that support must be used consistent with international law, to include the Law of War, and obligations related to protecting civilians,” Pentagon spokesperson Brig. Gen. Patrick Ryder told reporters Thursday.

One senior DOD official said that in private conversations, Pentagon officials have been asking the IDF to “think through their operations” and take into account the lives of innocent civilians.

The scrutiny of Israeli operations behind the scenes comes as Biden administration officials also ramp up pressure in public. Secretary of State Antony Blinken told reporters in Israel Friday that during a meeting with Prime Minister Benjamin Netanyahu he had urged Israel to pursue a pause in the fighting, and gave advice about reducing civilian casualties. In public remarks, Netanyahu responded he wouldn’t agree to humanitarian pauses and that Israel’s campaign would proceed “with full force” until Hamas released all its hostages.

Before Israel’s ground operation into Gaza, the Biden administration had been urging Israel to conduct a “more surgical” operation instead of a full-scale invasion due to the high potential for both civilian and IDF casualties, said the first U.S. official.

But Israel only “partially” took Washington’s advice, the official continued. “The path they chose was kind of splitting the difference.”

The message coming from Senate Democrats has already turned more critical of Israel.

Sen. Chris Murphy (D-Conn.), who leads the Senate Foreign Relations Committee’s Middle East panel, said Thursday the civilian death toll in Gaza was “unacceptable and unsustainable,” calling on Israel to switch to a counterterrorism campaign. Then Murphy and 13 of his colleagues, led by Sen. Tim Kaine (D-Va.), issued a joint statement in support of humanitarian pauses in the war.

Joe Gould contributed to this report.