When President Joe Biden thinks about unfinished legacy issues, I hope he will put taking decisive action to help the war-ravaged civilian population of Gaza at the top of his list.

The burden of civilian suffering in the year-long Gaza conflict is intolerable. Israeli defense leaders told the Biden administration several months ago that they had achieved their major military goals there. But the war continues, in part because Israeli Prime Minister Benjamin Netanyahu has no clear plans for a transition.

Top Biden administration officials tell me they recognize a moral and strategic obligation to provide humanitarian assistance for Palestinian civilians ravaged in this war. Senior officials speak about the failure of U.S. policy to protect civilians with a tone that reflects anguish, perhaps shame.

The self-criticism is warranted. Biden’s team has tried to protect civilians but too often failed.

The Gaza humanitarian issue might come to a head this week when Israel must respond to an Oct. 13 letter from Antony Blinken and Lloyd Austin, secretaries of state and defense, respectively. That letter threatened a cutoff of military aid if Israel didn’t address the “increasingly dire” humanitarian situation in Gaza.

The Blinken-Austin letter cited 15 specific humanitarian problems and warned that the administration, under law, would have to make an “assessment” of Israel’s response before providing more military aid. In diplomatic language, the letter catalogued the humanitarian horror in Gaza. “Extreme overcrowding,” with 1.7 million Gazans crammed in relief camps along the coast. Trucks carrying relief supplies “delayed at crossing platforms.” Relief agencies “unable to meet essential survival needs.”

The letter has teeth because it’s backed by a national security memorandum issued in February to implement an existing law that requires countries receiving U.S. weapons to respect human rights. Republicans denounced the memorandum and said its aim was “to placate critics of security assistance to our vital ally Israel.” President-elect Donald Trump hasn’t directly addressed the issue.

The Erez crossing at Gaza’s northern border has been reopened, a new crossing into central Gaza has been opened near the Israeli kibbutz of Kissufim, and a corridor from Jordan has been reopened. The Gaza coastal road is being cleared of debris, and Israel is adding new routes for delivery of relief supplies to circumvent looters. The refugee area along the coast is being expanded eastward.

The new Israeli steps will help, but they don’t come close to addressing the magnitude of the problem in Gaza. “I don’t think people grasp what a slaughterhouse this is,” said J. Stephen Morrison, who heads global health studies at the Center for Strategic and International Studies. He notes Gaza Health Ministry estimates of about 43,000 dead, 102,000 injured and 25,000 with lost limbs — but says final casualty numbers are likely to be considerably higher.

Israel keeps taking half steps, which the Biden administration accepts. The administration has told Israel that says a minimum of 350 relief trucks a day are needed. The Israeli cabinet Sunday night approved 250. How will Biden respond?

Gaza’s suffering might become even worse as the last shreds of the U.N. safety net collapse. The Israeli parliament last month passed a law blocking United Nations Relief Works Agency (UNRWA) operations across Israel and East Jerusalem. That could effectively halt the U.N. agency’s role in supplying food, medicine, water and schooling for Palestinian civilians.

The Knesset’s action was a direct repudiation of a Biden administration request. The Blinken-Austin letter had warned that the anti-UNRWA law “would devastate the Gaza humanitarian response … and deny vital educational and social services.” The Knesset passed it anyway.

For the Biden team, getting Israeli cooperation has been like “pulling teeth,” as one official put it. In the first days of the war, Blinken spent hours pleading with Netanyahu to begin aiding civilians. A trickle of aid started to flow, but in January, Israeli protesters blocked relief shipments through the Kerem Shalom crossing and police did nothing. At Blinken’s request, Israeli Defense Minister Yoav Gallant intervened and the trucks began moving again. But last week Netanyahu fired Gallant, the administration’s most reliable Israeli contact.

Watching each horror has added to the administration’s anguish — and its sense of powerlessness. It’s a last test for the outgoing president. If Israel doesn’t take immediate measures to protect civilians in Gaza, the United States is legally bound to stop supplying weapons for a war that should have ended months ago.

David Ignatius is a Washington Post columnist.