It took weeks of secret negotiations involving U.S., Israeli, Qatari and Egyptian officials, the heads of the CIA and the Mossad, and the personal intervention of President Joe Biden to convince a reluctant Israeli Prime Minister Benjamin Netanyahu to accept a four-day cease-fire that is expected to free 50 hostages from Hamas.

The negotiations, while ultimately successful, revealed the vast challenges that remain in freeing all of the roughly 240 captives seized during the group’s Oct. 7 terrorist attack on Israel.

Throughout the talks, Hamas officials maintained that they had taken captive only about 70 Israeli soldiers and 50 women and children, according to a diplomat in the region with knowledge of the negotiations.

Hamas officials said the whereabouts of as many as 100 other captives are unknown but they are pursuing leads. The group claimed that “some Israelis were kidnapped by individual Palestinian gangs or smugglers,” according to the diplomat.

The final agreement — the outlines of which had been on the table for weeks — wouldn’t have been accepted by Netanyahu without enormous pressure from Biden, according to a senior Israeli government official.

“This deal was a Biden deal, not a Netanyahu deal,” the official said.

Getting to work immediately

American and Qatari efforts to secure the release of hostages began hours after the deadly Oct. 7th attack, which killed 1,200 people and was the worst terrorist attack in Israel’s history.

The diplomat said Hamas leaders were stunned by the success of the operation. “They said it was a chaotic situation, a lot of people went in,” said the diplomat, referring to Palestinians streaming into southern Israel after Hamas fighters breached a border fence in roughly 30 places.

At the same time, Israeli officials, horrified by Hamas’ killings of hundreds of civilians, said they were “not willing to entertain in any way a conversation with Hamas,” said the diplomat, adding, “there was zero trust between to the two parties.”

A Biden administration official later described the negotiations as an “extremely excruciating five-week process.”

As Israeli air strikes in Gaza intensified, U.S. officials called for pauses in the fighting so food and aid could be delivered. They later called for the creation of humanitarian corridors so Palestinian civilians in northern Gaza could move south, officials said.

At the same time, representatives from Qatar, the oil-rich Arab nation where many of Hamas’ political leaders are based, again tried to broker talks.

Netanyahu, who was focused on destroying Hamas, put David Barnea, the head of the Mossad, Israel’s foreign intelligence service, in charge of negotiations.

The Israelis wanted the starting point for talks to be the immediate release of all hostages, a demand that Yahye Sinwar, the hardline leader of Hamas in Gaza, was bound to refuse, Moti Cristal, a veteran Israeli hostage negotiator, told NBC News.

“He has to have some hostages to use as human shields for himself,” Cristal said of Sinwar.

So the Israelis began negotiating, via U.S., Qatari and Egyptian intermediaries, the release of captured women and children, Cristal said.

In Washington, National Security Council officials told Brett McGurk, the White House’s Middle East coordinator, and Joshua Geltzer, the National Security Council’s top lawyer, to secretly participate in the talks.

On Oct. 13, Biden had an agonizing conversation via Zoom with the families of Americans who were thought to be hostages. A week later, a potential model for releasing captives emerged. On Oct. 20, two U.S. hostages, Judith Raanan and her daughter, Natalie, were freed.

As Israeli bombing continued, the rising Palestinian death toll slowed talks. More than 14,000 people, including 5,000 children, have been killed in Gaza, according to the enclave’s Hamas-controlled health department.

“The dynamic on the ground affected the talks,” said the diplomat. “Every time there was a big death toll.”

Israel’s requirement that Hamas provide identifying information and “proof of life” for the hostages also slowed negotiations. So did Hamas’ demand that more trucks carrying aid and fuel be allowed to enter Gaza.

‘The real breakthrough’

The diplomat said discussions finally began to move forward when Israeli ground forces gained firm control of much of northern Gaza.

“The real breakthrough happened when the north started to become more controlled by the Israelis,” the diplomat said. “They became more flexible.”

Biden also remained deeply involved, speaking repeatedly with Netanyahu and the Qataris, and receiving sometimes hourly updates from aides, U.S. and Israeli administration officials said.

As an agreement began to take shape, CIA director William Burns met in Qatar with David Barnea, the head of the Mossad, and Sheikh Tamim bin Hamad al-Thani, the country’s emir, on Nov. 9.

Several last-minute issues nearly derailed the talks, according to the diplomat in the region and Israeli officials. Hamas demanded that Israel release Palestinian prisoners, that more aid trucks be allowed into Gaza and that Israeli drone surveillance flights end.

“Surveillance was one of the obstacles,” the diplomat said. “It was a deal-breaker for Hamas.”

Eventually, compromises were reached. The two sides agreed that Israel would release 150 Palestinian prisoners, hundreds of aid trucks would enter Gaza and that no drone flights would occur for six hours a day.

When presented the final terms of the agreement, Netanyahu rebuffed a Hamas request for a five-day cease-fire, insisting on four. “Just a couple of days ago Biden came with the final deal saying a five-day pause and Netanyahu said four days,” a senior Israeli government official told NBC News.

After Hamas agreed to a four-day ceasefire, it seemed that a deal had finally been reached.

A final hurdle

A final obstacle emerged in Jerusalem, where right-wing Israeli politicians opposed the four-day cease-fire, saying it would benefit Hamas militarily.

“A debate erupted in the last three or four days (about) what is Israel’s No. 1 priority,” Cristal recalled. “Whether it is the release of the hostages or continuing to dismantle Hamas’s military and governing capabilities.”

After a seven-hour debate on Tuesday, a majority of Israel’s Cabinet members voted in favor of the agreement. On Wednesday, Qatari officials announced that a deal had been struck.

The diplomat with knowledge of the talks said they hoped the ceasefire and prisoner exchange would serve as confidence-building measures. Israel officials have said that, for every 10 additional hostages released, the truce can be extended by a day.

“The first release will break the mistrust,” said the diplomat. “We’ll start with the first group, then the second group and then the third group.”

Enormous challenges remain, particularly Hamas’ claims that it does not have control over as many as 100 of the roughly 240 hostages.

Nadav Eyal, a prominent Israeli columnist and commentator, said that many Israelis believe the destruction of Hamas must be the country’s primary goal. An October poll by the Israel Democracy Institute found that 45% opposed prisoner swaps, while 40% supported them.

“What people in the U.S. should know is Israelis don’t see this deal at all as a gate for a long-lasting cease-fire because the aim is to eliminate the military force of Hamas,” Eyal said. “It’s a consensus in Israel, and it’s not going to go away after the four days of the pause or truce.”