Explained | What we know about the Hamas attack and Israel's response

Prime Minister Benjamin Netanyahu on Sunday warned Israelis to brace themselves for a long and difficult war, a day after Hamas, the Palestinian militant group that controls the Gaza Strip, launched its largest surprise attacks in decades.

Israel responded with huge strikes on cities in the blockaded Gaza Strip, destroying dozens of buildings, as Hamas continued to fire rockets into Israel. So far, at least 500 people have been killed in Israel and Gaza, authorities said, with the death toll expected to rise.

Israelis have been left asking how their government, military and intelligence agencies appeared to be taken by surprise by such an assault, which is without recent precedent in its complexity and scale.

Here’s what you need to know about the Hamas attacks and Israel’s response.

How did Hamas carry out the attacks?

Hamas began firing thousands of rockets Saturday morning, striking targets as far away as Tel Aviv and the outskirts of Jerusalem, which rarely see any direct hits because of Israel’s sophisticated Iron Dome missile defense system.

About an hour after the first rocket attacks, Hamas militants crossed into Israel by land, sea and air, according to the Israeli military, leading to some of the first pitched battles between Israeli and Arab forces on Israeli soil in decades.

The militants infiltrated 22 Israeli towns and army bases and took civilians and soldiers hostages, many of whom they brought back to Gaza. At least 250 Israelis had been reported dead by officials as of late Saturday, and more than 1,400 were wounded.

What reasons did Hamas give?

Muhammad Deif, leader of the military wing of Hamas, said in a recorded message that the group had decided to launch an “operation” so that “the enemy will understand that the time of their rampaging without accountability has ended.”

He cited Israel’s occupation of the West Bank, which it captured during the Arab-Israeli war of 1967, recent Israeli police raids on the Al-Aqsa Mosque in Jerusalem, and the detention of thousands of Palestinians in Israeli jails.

The Al-Aqsa Mosque compound, revered by Muslims as the Noble Sanctuary and by Jews as the Temple Mount, is among the most deeply contested sites in the holy land.

How has Israel responded so far?

“We are at war and we will win it,” Netanyahu said in a televised statement Saturday, announcing a call-up of Israeli military reservists. Tank units have been sent to the south, fueling speculation that Israel may send ground forces into Gaza; the border in the north has been reinforced; and soldiers were still battling on Sunday to drive militants out from some communities infiltrated in the south.

Israeli jets launched airstrikes on Gaza, which Israel’s military said had destroyed centers that house Hamas militants. Palestinian officials said a hospital had been hit, along with multistory buildings, homes and a mosque. As of Sunday morning, the Palestinian Health Ministry in Gaza said at least 313 Palestinians had been killed and 1,990 injured — most inside Israel and the rest in the enclave.

Gaza has been under a suffocating Israeli blockade, backed by Egypt, since Hamas seized control of the coastal strip in 2007. The blockade restricts the import of goods, including electronic and computer equipment, that could be used to make weapons and prevents most people from leaving the territory.

What’s different about this attack?

The relentless, deadly conflict between Israel and Palestinians has spanned two centuries. The fighting — including in May 2021, when Israeli police raided the Al-Aqsa Mosque, which in part helped set off an 11-day war between Israel and Hamas — has left thousands dead.

Sometimes, the bloodshed has been incited by Israel targeting militant leaders or responding to protests. Other times, violence has been set off by attacks from Hamas or other militants. In this case, there was no obvious flashpoint, and Israel’s intelligence community and government seem to have been caught by surprise.

The timing of the assault was notable, hitting Israel at one of the most difficult moments in its history. It came after months of profound anxiety about the cohesion of Israeli society and the readiness of its military, a crisis prompted by the far-right government’s efforts to reduce the power of the judiciary.

The attacks also came on the holiday of Simhat Torah, and nearly 50 years to the day since Israeli authorities were caught off-guard when invading forces from Egypt and Syria set off the start of the Yom Kippur War.

What happens now?

Netanyahu said early Sunday that the “first phase” of Israel’s response had come to an end, claiming that Israeli forces had fought off most Hamas militants inside its territory. Amid speculation that Israel was preparing for a substantial ground invasion of Gaza, he pledged to continue the offensive “without reservation and without respite.”

U.S. President Joe Biden and other world leaders condemned Hamas — which the United States classifies as a terrorist organization — saying they support Israel and its right to defend itself. Arab nations, including Saudi Arabia, have called for de-escalation, but have avoided blaming Hamas.

The conflict also jeopardizes a monthslong effort by Biden and his top aides to push Saudi Arabia to normalize diplomatic relations with Israel, its historical adversary. Saudi Arabia has never recognized the Jewish state out of solidarity with Palestinians but had seemed ready to change its policy.

The fighting also threatens to become a wider regional conflict with Hezbollah, the Lebanese Shiite militant organization that fought a war with Israel in 2006. Responding to a call from Hamas for armed groups in Lebanon to join its assaults on Israel, Hezbollah said in a statement that it was “closely following the important developments in the Palestinian situation with great interest.”

On Sunday, United Nations peacekeeping forces in southern Lebanon said the situation on the Lebanese-Israeli border was “volatile, but stable,” after an exchange of artillery and rocket fire by Hezbollah and Israel earlier in the day.