JERUSALEM — Prime Minister Netanyahu told the nation Saturday night that the military has opened a “second stage” in the war against Hamas by sending ground forces into Gaza and expanding attacks from the ground, air and sea.

Casting the war as a fight for his country’s very survival, he warned that the assault would intensify ahead of a broad ground invasion into the territory. Mr. Netanyahu, the Israeli press reported, quoted the biblical command to remember what the Amalekites did to the Israelites after the Exodus from Egypt. “We remember and we are fighting.”

“There are moments in which a nation faces two possibilities: to do or die,” Mr. Netanyahu said. “We now face that test and I have no doubt how it will end: We will be the victors. We will do and we will be the victors.”

The bombardment knocked out most communications in the territory and largely cut off the enclave’s 2.3 million people from the world. The military released grainy images showing tank columns moving slowly in open areas of Gaza, many apparently near the border, and said warplanes bombed dozens of Hamas tunnels and underground bunkers. The underground sites are a key target in Israel’s campaign to crush the territory’s ruling group after its bloody incursion into Israel three weeks ago.

The escalation ratcheted up domestic pressure on Israel’s government to secure the release of dozens of hostages seized in the October 7 rampage by Hamas, when militants stormed from Gaza into nearby Israeli towns and gunned down civilians and soldiers. The unprecedented attack during a major Jewish holiday — Simchat Torah — initiated a war between Israel and Hamas that could spread into a broader Mideast conflict.

Desperate family members met with Mr. Netanyahu on Saturday and expressed support for an exchange for Palestinian prisoners held in Israel, a swap floated by the top Hamas leader in Gaza.

Mr. Netanyahu told the nationally televised news conference that Israel is determined to bring back all the hostages, and maintained that the expanding ground operation “will help us in this mission.” He said he couldn’t disclose everything that is being done due to the sensitivity and secrecy of the efforts.

“This is the second stage of the war, whose objectives are clear: to destroy the military and governmental capabilities of Hamas and bring the hostages home,” he said in his first time taking questions from journalists since the war began.

He didn’t address calls for a cease-fire, but in a speech peppered with references to centuries of Jewish history and military conflicts, made clear his view that Israel’s future depends on its success against “enemy” forces.

“Our heroic soldiers have one supreme goal: to destroy the murderous enemy and ensure our existence in our land. We have always said, ‘Never again,'” he said. “‘Never again’ is now.”

Netanyahu also acknowledged that the October 7 “debacle,” in which more than 1,400 people were killed, would need a thorough investigation, adding that “everyone will have to answer questions, including me.”

The Israeli military said it was gradually expanding its ground operations inside Gaza, while stopping short of calling it an all-out invasion.

“We are proceeding with the stages of the war according to an organized plan,” said the chief military spokesman, Rear Admiral  Daniel Hagari. The comments hinted at a strategy of a staged escalation, instead of a massive and overwhelming offensive.

Early in the war, Israel amassed hundreds of thousands of troops along the border. Until now, troops had conducted brief nightly ground incursions before returning to Israel. Despite the Israeli offensive, Palestinian Arab terrorists have continued firing rockets into Israel, with the constant sirens in southern Israel a reminder of the threat.

The Palestinian Arab death toll in Gaza rose Saturday to just over 7,700 people since the war began, with 377 deaths reported since late Friday, according to the Gaza Health Ministry.

Most of those killed have been women and minors, the ministry said. The Gaza Health Ministry is controlled by Hamas, and its casualty statists are widely distrusted, including by President Biden, who warned of the statistics in a press conference Tuesday.

Israel says its strikes target Hamas fighters and infrastructure and that the militants operate from among civilians, putting them in danger. The World Health Organization appealed to “the humanity in all those who have the power to do so to end the fighting now” in Gaza.

More than 1.4 million people across Gaza have fled their homes, nearly half crowding into U.N. schools and shelters, following repeated warnings by the Israeli military that they would be in danger if they remained in northern Gaza.

The intensified air and ground campaign raised new concerns about hostages dragged into Gaza. On Saturday, hundreds of relatives gathered in Tel Aviv and demanded that the government put the return of their loved ones ahead of military objectives.

In comments likely to inflame these tensions, Hamas’s top leader in Gaza, Yahya Sinwar, said the Palestinian militant groups “are ready immediately” to release all hostages if Israel releases all Palestinian Arabs held in Israeli prisons. Admiral Hagari, the Israeli military spokesman, dismissed the offer as “psychological terror.”

In Cairo, President el-Sissi said his government was working to de-escalate the conflict through talks with the warring parties to release prisoners and hostages. On Saturday, he spoke with  Secretary-General Guterres of the UN, his office said.

Guterres in a statement said he was “surprised by an unprecedented escalation of the bombardments and their devastating impacts” in Gaza. President Erdogan told hundreds of thousands of people at a pro-Palestinian rally in Istanbul that his country was preparing to proclaim Israel a “war criminal” for its actions in Gaza. He did not give details. Israel’s foreign minister said he ordered the return of Israel’s diplomatic mission from Turkey to reassess ties. 

The conflict has threatened to ignite a wider war across the region. Arab nations — including American allies and ones that have reached peace deals or normalized ties with Israel — have raised increasing alarm over a potential ground invasion.