In talking to Netanyahu, Biden was more direct than in prior calls that the Israeli military should take pains to avoid civilian casualties, the U.S. officials said. Biden’s message suggests the White House will be attuned to any blowback if Israel is seen as using excessive force resulting in the deaths of women, children and non-combatants.

Biden made clear in a 10-minute address Tuesday after his phone call with Netanyahu that he stands with Israel and will commit U.S. military aid to protect the country from future attacks.

“Like every nation in the world, Israel has the right to respond — indeed has a duty to respond — to these vicious attacks,” Biden said.

An open question since Hamas launched its surprise attack over the weekend is whether Biden will give Netanyahu a free hand to rout Hamas by any means necessary — or insist that he throttle back if civilian deaths in Gaza start to pile up.

In his speech, Biden said that in his phone call with Netanyahu he, “told him if the United States experienced what Israel is experiencing, our response would be swift, decisive, and overwhelming.”

He added, “We also discussed how democracies like Israel and the United States are stronger and more secure when we act according to the rule of law. Terrorists purposefully target civilians, kill them. We uphold the laws of war — the law of war. It matters.”

International laws of war call for avoiding the indiscriminate killing of civilians and proportionality.

American presidents have played a restraining role in the past. As Israel bombed Gaza in 2014 in response to Palestinian rocket attacks, then-President Barack Obama called on both sides of the conflict “to act with reasonableness and restraint.”

Biden faces competing pressures from inside his party and out as to how Israel conducts the war. As a close ally of Israel that has provided billions of dollars in weapons to the country over the years, the U.S. typically has great sway in Jerusalem.

Far-right Republicans want Israel to lead an unfettered assault that vanquishes Hamas and prevents such attacks from happening again.

“I’ll say this to Prime Minister Netanyahu: Finish them,” Nikki Haley, a Republican presidential candidate and former U.S. ambassador to the United Nations in the Trump administration, told Fox News.

But a left-wing faction of the Democratic Party has criticized Israel’s treatment of Palestinians living in the West Bank and Gaza. Some liberal House members have called on Biden to cut off aid to Israel unless Palestinians are accorded more rights.

Rep. Cori Bush, D., Mo., wrote in a social media post on Saturday that, “we must do our part to stop this violence and trauma by ending U.S. government support for Israeli military occupation and apartheid.”

But the divide isn’t quite so precise. Horrified by the brutal attack and threat to Israel’s sovereignty, people close to his administration want to see Israel mount a counterattack that guarantees its safety for years to come.

Tom Nides, the Biden administration’s former ambassador to Israel, said in an interview that Hamas, though it lives alongside Palestinians, is heedless of their suffering.

“The goal of Hamas is to create a regional war against the state of Israel,” Nides said. “And they don’t care what the costs will be for that to be created, including the death and destruction of innocent Palestinians.”