Some factions had signed accords with Israel, meant to pave the way for a two-state solution. The Palestinian Authority, envisioned as a Palestinian government in waiting, had limited authority over parts of the West Bank and remained officially committed to negotiating an end to the conflict.
Hamas, meanwhile, effectively sought to undo history, starting with 1948, when more than 700,000 Palestinians fled or were expelled from their homes in what would become Israel during the war surrounding the foundation of the Jewish state.
For Hamas, that displacement, along with Israel’s occupation of the West Bank and Gaza during the 1967 Mideast war, were great historical wrongs that had to be righted by force of arms. Hamas dismissed peace talks with Israel as a betrayal, viewing them as a capitulation to Israel’s control over what the group considered occupied Palestinian land.
The Palestinian political rift became etched into geography in 2007, when Hamas won a bout of factional fighting in Gaza and took charge of the territory. Suddenly, it was not just fighting Israel, but also governing Gaza. Israel, in tandem with Egypt, imposed a blockade on the strip aimed at weakening Hamas, plunging Gazans into deepening isolation and poverty.
By the time Mr. Sinwar returned to Gaza, Hamas was already entrenched as the de facto government and had settled into what Tareq Baconi, a Hamas expert, has called a “violent equilibrium” with Israel. Deep hostility frequently erupted into deadly exchanges of Hamas rockets and Israeli airstrikes. But most of Gaza’s commercial goods and electricity came from Israel, and Hamas often sought to loosen the blockade during cease-fire talks.
Hamas leaders were ambivalent about the group’s new governing role, with some believing they needed to improve life for Gazans, and others considering governance a distraction from their original, military mission, experts say. Hamas derided the Palestinian Authority for its cooperation with Israel, including the use of Palestinian police to prevent attacks on Israel. Some Hamas leaders feared that their own group, in negotiating daily life issues with Israel, was, in a lesser way, on the same path.
In 2012, Mr. Sinwar became the armed wing’s representative to Hamas’s political leadership, linking him more tightly to the leaders of the military wing, including Mr. Deif, the mysterious head of the Qassam Brigades. The two men were key architects of the Oct. 7 attack, according to Arab and Israeli officials.
When Mr. Sinwar became the overall head of Hamas in Gaza in 2017, he sometimes projected an interest in accommodation with Israel. In 2018, he gave a rare interview to an Italian journalist working for an Israeli newspaper and appealed for a cease-fire to ease the suffering in Gaza.
“I am not saying I won’t fight anymore,” he said. “I am saying that I don’t want war anymore. I want the end of the siege. You walk to the beach at sunset and you see all these teenagers on the shore chatting and wondering what the world looks like across the sea. What life looks like,” he added. “I want them free.”
Hamas also issued a political program in 2017 that allowed for the possibility of a two-state solution, while still not recognizing Israel’s right to exist.
Israel granted some concessions, agreeing in 2018 to allow $30 million per month in aid from Qatar into Gaza and increasing the number of permits for Gazans to work inside Israel, bringing much needed cash into Gaza’s economy.
Violence continued to break out. In 2021, Hamas launched a war to protest Israeli efforts to evict Palestinians from their homes in East Jerusalem and Israeli police raids of the Aqsa Mosque in Jerusalem’s Old City.
That was a turning point, Osama Hamdan, a Hamas leader based in Beirut, Lebanon, told The Times. Instead of firing rockets over issues in Gaza, Hamas was fighting for concerns central to all Palestinians, including those outside the enclave. The events also convinced many in Hamas that Israel sought to push the conflict past a point of no return that would ensure the impossibility of Palestinian statehood.
“The Israelis were only concerned with one thing: How do I get rid of the Palestinian cause?” Mr. Hamdan said. “They were heading in that direction and not even thinking about the Palestinians. And if the Palestinians did not resist, all of that could have taken place.”
Still, in 2021, Israeli military intelligence and the National Security Council thought that Hamas wanted to avoid another war, according to people familiar with the assessments.
Hamas, too, bolstered the idea that it was prioritizing governing over battle. Twice, the group refrained from joining clashes with Israel started by Palestinian Islamic Jihad, a smaller militia in Gaza. Hamas’s political leaders were trying through mediators in Qatar to increase the aid going into Gaza and the number of laborers going out to work in Israel, according to diplomats involved in the discussions.
Many in Israel’s security establishment also came to believe that its complex border defenses to shoot down rockets and prevent infiltrations from Gaza were enough to keep Hamas contained.
But inside Gaza, Hamas’s capabilities grew.
By Oct. 7, Hamas was estimated to have 20,000 to 40,000 fighters, with about 15,000 rockets, mainly manufactured in Gaza with components most likely smuggled in through Egypt, according to American and other Western analysts. The group had mortars, anti-tank missiles and portable air-defense systems as well, they said.
Mr. Sinwar had also restored the group’s ties to its longtime backer, Iran, which had frayed in 2012, when Hamas shuttered its office in Syria, a close Iranian ally, amid Syria’s civil war.
That restoration deepened the relationship between Hamas’s military wing in Gaza and the so-called axis of resistance, Iran’s network of regional militias, according to regional diplomats and security officials. In recent years, a stream of Hamas operatives traveled from Gaza to Iran and Lebanon for training by the Iranians or Hezbollah, adding a layer of sophistication to Hamas’s capabilities, the officials said.