WASHINGTON (AP) — Facing heat over its military support for Israel's war, the Biden administration is due to deliver a first-of-its-kind formal verdict this week on whether the airstrikes on Gaza and restrictions on delivery of aid have violated international and U.S. laws designed to spare civilians from the worst horrors of war.

A decision against close ally Israel would add to pressure on President Joe Biden to curb the flow of weapons and money to Israel's military. The Democratic administration took one of the first steps in that direction in recent days, when it paused a shipment of 3,500 bombs out of concern over Israel's threatened offensive on Rafah, a southern city crowded with more than a million Palestinians, a senior administration official said.

The administration agreed in February at the insistence of Democrats in Congress to a negotiated agreement mandating it look at whether Israeli forces in Gaza have used U.S.-provided weapons and other military assistance in a lawful manner.

Additionally, under the agreement, it must tell Congress whether it deems that Israel has acted to "arbitrarily deny, restrict, or otherwise impede, directly or indirectly," delivery of any U.S.-supported humanitarian aid into Gaza for starving civilians there.

Officials said Wednesday they would not meet the day's deadline for the report to be delivered to Congress, but expected it would still come this week. They spoke on condition of anonymity to discussion internal administration deliberations.

Israel's campaign to crush the Hamas militant group after its surprise October attack — and the ensuing disaster for Gaza's civilians — have fueled a debate about whether the United States should act on grave human rights violations by one of its foreign recipients of military support when it sees them, as advocates say U.S. law requires, or only when it deems doing so serves U.S. strategic interests.

"While human rights is an important component of the national interest, American priorities are much broader — particularly in an era of strategic competition," Idaho Sen. Jim Risch, the top Republican on the Senate Foreign Relations Committee, and GOP Rep. Michael McCaul of Texas, the House Foreign Affairs Committee chairman, wrote last week in urging to Biden to repeal his February directive.

But Maryland Sen. Chris Van Hollen, the Democrat who spearheaded congressional negotiations with the White House to mandate the review, told reporters he feared the administration may allow policy aims to shape the outcome of its review. Van Hollen said he supports a strong security partnership with Israel but believes the U.S. should apply standards evenly.

Israel is the largest recipient of U.S. security assistance. Palestinian suffering in the war in Gaza has churned up protests and other challenges for Biden at home and abroad as he seeks reelection against former President Donald Trump, a Republican.

The administration's findings must be "seen to be based on facts and law, and not based on what they would wish it would be," Van Hollen told reporters last week.

At the time the White House agreed to the review, it was working to head off moves from the Democratic lawmakers and independent Sen. Bernie Sanders of Vermont to start restricting shipments of weapons to Israel.

Israel launched its offensive after attacks led by Hamas killed about 1,200 people on Oct. 7. Nearly 35,000 Palestinian civilians, two-thirds of them women and children, have been killed since then, according to local health officials. U.S. and U.N. officials say full-fledged famine has set in in northern Gaza, owing to Israeli restrictions on food shipments and to the fighting.

Human rights groups long have accused Israeli security forces of committing abuses against Palestinians and have accused Israeli leaders of failing to hold those responsible to account. In January, in a case brought by South Africa, the top U.N. court ordered Israel to do all it could to prevent death, destruction and any acts of genocide in Gaza, but the panel stopped short of ordering an end to the military offensive.

Israel says that it is following all U.S. and international law, that it investigates allegations of abuse by its security forces and that its campaign in Gaza is proportional to the existential threat it says is posed by Hamas.

As the suffering of Palestinian civilians grew, Biden and his administration edged away from their initial unwavering public support of Israel and began to criticize its conduct of the war.

Biden in December said "indiscriminate bombing" was costing Israel international backing. After Israeli forces targeted and killed seven aid workers from the World Central Kitchen in April, the Biden administration for the first time signaled it might cut military aid to Israel if it didn't change its handling of the war and humanitarian aid.

Republican Ronald Reagan was one of the last presidents openly to suspend some U.S. support for Israel's military as a way to pressure Israel over its offensives.

Under a 1997 congressional act known as the Leahy law, when the U.S. finds credible evidence that a unit of foreign security forces has committed gross human rights abuses, any U.S. aid to that unit is supposed to be automatically suspended.

Secretary of State Antony Blinken wrote House Speaker Mike Johnson, R-La., last week that the U.S. found the evidence of such abuses by one particular Israeli unit to be credible. Blinken added that Israel had yet to rectify the unit's wrongdoing, something the Leahy law says must happen for any suspension of military aid to be lifted. Blinken said rather than suspend the aid, the U.S. would work with Israel to "engage on identifying a path to effective remediation for this unit."

Israeli officials have identified it as the Netzah Yehuda, which is accused in the death of a Palestinian American man and other abuses in the Israeli-occupied West Bank before the latest war in Gaza.

Tim Rieser, a veteran Senate foreign policy staffer who helped now-retired Sen. Patrick Leahy craft the law, said if it had been applied to Israel, "maybe it would have been a deterrent."

Instead, "what we've seen is that abuses against Palestinians are rarely punished," Rieser told The Associated Press.

While a finding against Israel under the national security memo wouldn't obligate the administration to start cutting military support for Israel, it would increase pressure on Biden to do so.

A report to the administration by an unofficial, self-formed panel of military experts and former State Department officials, including Josh Paul and Charles Blaha, points to specific Israeli strikes on aid convoys, journalists, hospitals, schools and refugee centers and other targets broadly protected by law. The report argues the administration must find Israel's conduct in Gaza has violated the law. Amnesty International has argued the same.

The high civilian death tolls in Israel's strikes go far beyond the laws of proportionality, the U.S. critics and rights groups say. They point to an Oct. 31 strike on a six-story apartment building in Gaza that killed at least 106 civilians. Critics say Israel provided no immediate justification for that strike.

"They're taking what we did in Mosul and Raqqa, and going tenfold beyond," exceeding even what was allowed under U.S. rules of engagement at the time in the so-called war on terror, said Wes Bryant, a former Air Force targeting expert who led strike cells against the Islamic State and other extremist groups in Afghanistan, Iraq and Syria. He is among those urging the U.S. to condition military support to Israel.

"If this is the new bar for 21st-century warfare, we might as well go back to World War II," Bryant said.

Israel and the Biden administration say Hamas' presence in tunnels throughout Gaza, and alleged presence in hospitals and other protected sites, make it harder for Israeli forces to avoid high civilian casualties.