He had already spoken on the phone with Israeli Prime Minister Benjamin Netanyahu, Biden said later that day in a forceful statement from the White House State Dining Room. “The United States stands with Israel … . We will not ever fail to have their back,” he declared, calling his administration’s support for Israeli security “rock solid and unwavering.”

U.S. defense and intelligence officials had been ordered “to make sure Israel has what it needs” to defend itself against the Hamas terrorist attack, the president said. U.S.-made Israeli warplanes were already striking inside Gaza.

It was not the first such scene of carnage for current and former U.S. officials with long experience in the volatile Middle East, who have witnessed decades of episodic battles between Israel and its enemies in the region. On the day the war in Gaza began six months ago Sunday, they thought it would probably be over within weeks. At most in a couple of months. Certainly by Christmas.

Tens of thousands of Palestinian civilian deaths later, the war goes on, largely unabated. Frustrated and sometimes furious with a Netanyahu government that has often ignored its advice on how to conduct military operations in Gaza and publicly rejected U.S. visions for a permanent peace, the Biden administration now finds itself in a policy cul-de-sac from which there is no easy exit.

This account of the past six months of brutal war and difficult diplomacy comes from previous reporting throughout the conflict, and recent public statements and interviews with regional experts and multiple senior administration officials, some of whom spoke on the condition of anonymity to describe internal deliberations.

Many Hamas fighters have been killed, but thousands remain in the fight, their senior leaders believed to be hidden — along with many of the remaining hostages — in tunnels deep below ground. While the United States and allies in the region plead for a cease-fire to allow a hostage release and for aid to flow to starving Gazans, the two sides are locked in what both consider an existential battle.

Much of Gaza, a sliver of land the size of Las Vegas with three times the population, has been reduced to rubble by Israeli air and ground attacks. Most of its 2.1 million people have been displaced by the fighting, many fleeing into an area around the southernmost city of Rafah, where they live in squalid camps with little food and even less hope.

International support for Israel in the immediate wake of Hamas’s invasion — which saw the killing of about 1,200 Israelis and the taking of around 250 hostages — has turned to outrage and charges of Israeli war crimes. To much of the world, the U.S. backing for Israel’s war effort has left the administration morally compromised, even complicit in the destruction and death.

At home, in what is already a contentious election year, Biden is stuck between a Republican Party demanding support for Israel at all costs, and increasing numbers of Democrats demanding he stop the steady stream of weapons sent to Jerusalem. His campaign stops are frequently disrupted by pro-Palestinian protests.

Administration officials maintain that things, as bad as they are, would be worse still had they not successfully pushed for changes in Israel’s war tactics, and persuaded Netanyahu to lift his government’s embargo on all supplies of food, water and fuel into Gaza. The negotiation that won a week-long cease-fire in November and brought about half the hostages home was a bright spot, one they had hoped would be followed by a longer and more significant pause in the fighting.

In Israel, Netanyahu’s right-wing government coalition has its own troubles. Enraged and traumatized by the Hamas attacks, most Israelis want Gaza destroyed. But many also blame their prime minister for allowing the terrorist invasion to happen in the first place and accuse him of abandoning the hostages. Tens of thousands have taken to the streets to demand new elections.

“We have arrived at a terrible milestone,” Martin Griffiths, the senior U.N. official for humanitarian affairs, said in a statement Saturday. “For the people of Gaza, the past six months of war have brought death, devastation and now the immediate prospect of a shameful man-made famine. For the people affected by the lasting horror of the 7 October attacks, it has been six months of grief and torment.”

The United States was the first country in the world to recognize Israel’s independence in May 1948. But even as it has long supplied the weapons for Israel to defend itself, it has sometimes pressured Israel to stop using them. When Israeli forces occupied parts of the Sinai, President Dwight D. Eisenhower in early 1957 bucked congressional opposition and threatened trade sanctions and a suspension of military aid if they did not withdraw. It worked, and Israeli troops spared the surrounding Egyptian Third Army and left the desert territory.

Henry Kissinger’s shuttle diplomacy during the presidency of Richard M. Nixon ultimately ended the 1973 war between Israel and Egypt with a land-for-peace deal that led to Egypt becoming the first Arab country to recognize Israel as a legitimate state. In early 1991, the United States strong-armed Israel into not responding to Saddam Hussein’s Scud missile attacks on its territory, fearing a wider Middle East conflict and saying that it would handle Saddam itself.

Since Hamas took over Gaza after winning parliamentary elections in 2006, it has been engaged in at least four separate, relatively brief direct conflicts with Israel. U.S. involvement was limited to defending Israel’s right to security and protecting it from censure in the United Nations.

But the circumstances of the current conflict, the devastation wrought, and the length of time it has gone on have shined a harsh light on the limitations of any control the United States might have thought it had over Israel’s actions.

“The influence of any outside party — even one that has theoretically on paper an enormous amount of influence on Israel — is limited,” said Aaron David Miller of the Carnegie Endowment for International Peace, a former diplomat who spent nearly three decades working on Israeli-Palestinian relations in both Republican and Democratic administrations.

“The Middle East is literally littered with the remains of great powers who believed they could impose their limits” on the actions of those who live there, Miller said.

Many factors make this situation unique. Though Biden has had a complicated relationship with Netanyahu, the president is said to have a deep-seated, personal commitment to Israel that goes back to his first years as a U.S. senator. But Netanyahu “is trying to save his political skin by performative opposition to Biden in his approach to Gaza,” said Jeffrey Feltman of the Brookings Institution, who served as top official on the Middle East at the Obama administration’s State Department before becoming U.N. undersecretary for political affairs.

Losing U.S. support in the past “would be an almost insurmountable obstacle for an Israeli politician,” Feltman said. And unlike Washington’s prior interventions to make peace between Israel and its Arab neighbors, the United States has no leverage at all against Hamas, a terrorist organization that is still holding upward of 100 hostages, including a handful of Americans.

Even as the scramble began in Washington to determine what to do about Gaza, the administration’s top national security team was equally, if not more concerned about preventing a wider regional conflagration. Other Iran-backed militant Islamic groups — Hezbollah in Lebanon, proxy militias in Syria and Iraq, the Houthis in Yemen — would be tempted to use the opportunity to open a new front on Israel’s borders.

Barely a week after the Hamas attack on Israel, Defense Secretary Lloyd Austin surged two aircraft carrier groups and thousands of U.S. troops to the eastern Mediterranean as a warning to others.

But the fury of Israel’s response inside Gaza quickly became impossible to ignore. On Oct. 18, Biden arrived in Israel, the first U.S. presidential visit during wartime, to demonstrate American support while reminding Netanyahu that “democracies like Israel and the United States are stronger and more secure when we act according to the rule of law.”

The core objective of Biden’s trip, one U.S. official said, was buying time for Israel “to think this through.”

Netanyahu and his war council were planning a full-scale ground assault into Gaza, where airstrikes by then had killed more than 3,000 Palestinians, according to local health authorities, and the Israeli blockade had left millions without adequate food or water. The Biden administration had almost immediately appointed a seasoned diplomat, David Satterfield, as its envoy for humanitarian issues in Gaza, with the urgent goal to get more assistance to besieged civilians.

But the opposing pressures that have buffeted U.S. policy since the crisis began were already apparent in two events that coincided with Biden’s visit. On the same day the U.S. president met with Netanyahu, the United States vetoed a U.N. Security Council resolution calling for a cease–fire. It was the only country to vote against the measure.

Two days later, Biden claimed credit for pressing Israel to allow the first 20 trucks full of aid to enter Gaza. The dissonance of the message — go ahead and wage total war, but try to do so humanely — was apparent.

After the initial flurry of activity in October, elements of the crisis began to repeat themselves.

Every few weeks, Secretary of State Antony Blinken traveled to Israel to express increasing concern about Israel’s war actions, and to neighboring Arab states to try to persuade them to help find a way to forge a postwar peace plan that Jerusalem couldn’t refuse.

By late November, as Israel prepared to move its scorched-earth campaign in northern Gaza to the southern part of the enclave where much of the population had relocated, senior administration officials began to voice their concerns more publicly. “We’ve been clear with the Israelis that we don’t support them moving forward with operations in the south unless they have a plan to deal with the now-increased level of civilians there,” White House national security spokesman John Kirby told reporters.

They can’t do in the south “what they did in the north,” said a senior administration official during the last week in November, when the announced Gazan death toll had passed 13,000. The administration was pushing for “areas of deconfliction” where Gazans seeking shelter would be “immune from kinetic activity,” the official said, and had urged the Israeli military to use smaller, more precise munitions.

Israel, officials said, was “receptive” to the message. But on a visit to troops inside northern Gaza that week, Netanyahu did not appear to be listening. “We continue until the end, until victory,” he said. “Nothing will stop us.”

Meanwhile, The Washington Post has reported, the Biden administration was continuing to send vast amounts of bombs and other munitions to Israel.

After a temporary cease–fire and partial hostage return collapsed in early December, amid renewed Hamas rocket attacks in Israel, Netanyahu delivered on his promise. As Israeli tanks and ground troops moved to surround the southern Gazan city of Khan Younis, civilian deaths increased during January and the number of aid trucks allowed to enter plummeted.

In his strongest public criticism to that point, Biden on Feb. 11 said Israel was losing international support because of its “indiscriminate bombing” of Gaza.

As the death toll neared 28,000, Biden told reporters after a phone conversation with Netanyahu that Israel’s campaign was “over the top.” A senior official who briefed reporters after the call said that protection of civilians was “a constant discussion between us and the Israelis,” even as Biden shared their goal of defeating Hamas.

In March, Blinken and Israeli leaders again confronted each other in Tel Aviv about the future of the war. The death toll in Gaza had climbed to 31,000. A U.N.-backed report said that famine may have already have reached the northern region and that more than half the enclave’s population faced catastrophic levels of hunger. The U.S. secretary of state urged Israel not to invade Rafah, where 1.4 million civilians were packed with nowhere else to go.

“We’ll do it by ourselves,” Netanyahu said defiantly.

Administration officials last week maintained that some progress had been made since the beginning of the year — a decrease in Israeli troops deployed inside Gaza, fewer indiscriminate airstrikes and an incremental uptick in trucks bearing aid.

But in recent days, as the six-month mark approached, the tenor of the administration’s entreaties to Israel has changed from plaintive finger-wagging to angry displeasure. On March 25, United States abstained for the first time on a U.N. resolution demanding an immediate cease-fire that was not directly tied to a hostage release, allowing it to pass.

Furious, Netanyahu canceled a face-to-face meeting in Washington, specifically requested by Biden, between his top advisers and their U.S. counterparts to discuss Israel’s plans for Rafah. A virtual meeting was held instead. Netanyahu, in a fiery speech to the Israeli public, called again for the total annihilation of Hamas and said that he had approved plans for an invasion of Rafah.

As if to underline the inconsistency of the administration’s messaging — and as more Democrats demand a cutoff of U.S. aid — the State Department has since authorized thousands more bombs to be sent to Israel.

The White House is clinging to the hope that a pause in the fighting can be won before too long. Top Israeli and U.S. intelligence officials are in Cairo this weekend to continue efforts to negotiate a new temporary cease-fire to allow more hostages to come home and more aid into Gaza. Biden wrote to the leaders of Egypt and Qatar on Friday to urge them to use whatever influence they have to pressure Hamas to agree.

In a statement, Hamas said it would send a delegation, but that its demands — including a permanent cease-fire and the complete withdrawal of “occupation” forces from Gaza — “would not be conceded.”

But recent provocations have further complicated talks. On April 1, an Israeli airstrike on an alleged consular facility in Damascus killed at least seven Iranian military officials said to be in charge of proxy activities in the Levant. Iran vowed to retaliate.

That same day, despite having cleared their travel inside Gaza with the Israel Defense Forces, three vehicles belonging to World Central Kitchen, a renowned international aid agency, were hit by missiles fired from an Israeli drone. Six Western aid workers, including an American, and their Palestinian driver were killed. Israel apologized and said it was a mistake.

Biden, reflecting the level of international fury that ensued, said he was “outraged and heartbroken” and for the first time threatened a change in U.S. policy toward Israel.

On Friday, Netanyahu’s government made it known that it had agreed to two long-standing U.S. demands — opening its Ashdod port and the main northern border crossing into Gaza at Erez for aid deliveries — and would institute a new, improved “deconfliction” system to avoid targeting humanitarian transports inside the enclave.

But the carnage in Gaza, and the fundamental incompatibility of Israel’s imperatives and U.S. demands, seems no closer to resolution.

Miller, of the Carnegie Endowment for International Peace, sees little way out for the administration. Asked where the war would be six months from now, with the U.S. election just weeks away, he said, “I would like to think the kinetic phase of Israel’s ground campaign is over. More hostages are out, more humanitarian aid is in. But you still can’t get around the reality that Israel is determined to kill the leadership of Hamas.”