Prime Minister Benjamin Netanyahu of Israel declared on Monday that his country is “on the eve of a forceful entry to Gaza” after his security cabinet approved a new plan for tens of thousands of additional soldiers to seize and hold territory in the embattled enclave and relocate Palestinians to the south.

In video posted to social media as military reservists across Israel began receiving notices of their call-up, Mr. Netanyahu said that the country’s top military officials had recommended what he called an “intensive” escalation of the 18-month war.

“It’s time to launch the concluding moves,” Mr. Netanyahu said the military officials told him, adding that the new campaign would help bring home the hostages still being held in Gaza. The prime minister said he believes “we are not done. We are before the finish line.”

The escalation followed more than two months in which Israel continued to blockade and bombard the Gaza Strip as cease-fire talks to free the remaining hostages ground to a near standstill. Israel has barred any humanitarian aid to Gaza in an effort to press Hamas to surrender, leading aid groups to denounce mounting deprivation among Palestinians there.

Mr. Netanyahu’s opponents quickly criticized the expanded military campaign, saying it would endanger the remaining hostages’ lives and would not fundamentally change the dynamic that 18 months of war has wrought. The prime minister’s critics — both inside and outside the country — have urged him to bring to an end a conflict that began when Hamas killed about 1,200 people in Israel on Oct. 7, 2023 and took some 250 hostage.

Israeli officials said the offensive would start slowly in anticipation of cease-fire negotiations that are ongoing ahead of President Trump’s trip next week to the region for meetings in several Arab capitals. But the officials said that if a deal is not reached soon, the expanded ground operation would commence in earnest.

Mr. Netanyahu vowed in the video that the decision to ramp up the fighting in Gaza does not mean Israel has abandoned hope for rescuing the remaining hostages.

“We will not give up on anyone,” he vowed.

David Mencer, a government spokesman, described the plan as a renewed effort to increase pressure on Hamas to release the hostages and to destroy all of Hamas’s infrastructure, both above and below ground. He said the campaign calls for the “holding of territories” by Israeli soldiers for an indefinite period of time “to prevent Hamas from taking it back.”

Mr. Mencer said the intent was not a permanent occupation of Gaza, a scenario that would almost certainly spur international objections, as would the forced relocation of Palestinians from their homes in the north.

Effie Defrin, the Israeli military spokesman, said in a televised statement that Israel’s operation will include “a wide attack, involving moving most of Gaza’s population. This is for their protection in an area clean of Hamas.”

At the White House, Brian Hughes, a spokesman for the National Security Council, did not comment directly on the Israeli announcement, but he said that Mr. Trump “remains committed to securing the immediate release of hostages and an end to Hamas rule in Gaza.” He added, “Hamas bears sole responsibility for this conflict and for the resumption of hostilities.”

But it was not clear how much of the announcement was primarily designed as a public display of action by Mr. Netanyahu after a cease-fire collapsed in March. The Israeli call-up of soldiers is seen as a message to Mr. Netanyahu’s hard-line supporters, some of whom were dismayed that the military had not completed the task of eradicating Hamas. Promising a more intense phase of the war could be good domestic politics for him.

It is also not obvious how additional fighters would fundamentally alter a dynamic seen over 18 months of war in which hundreds of thousands of soldiers have pummeled Hamas fighters, with residents in Gaza caught in the middle, but have failed to achieve Israel’s goals of destroying the militant group or releasing all hostages.

As part of the Israeli offensive, Israel would move “the Gazan population south for its own defense,” Mr. Mencer said. The plan echoed Israel’s actions earlier in the war, when Israel ordered a mass evacuation of northern Gaza before its ground invasion in late 2023.

An Israeli official, who spoke on condition of anonymity to discuss operational planning, said the understanding was that the Israeli military would move to capture more territory beyond what it was already holding, but the official cautioned that it was not clear whether Israel had plans to occupy all of Gaza at this point.

The cabinet also approved a new Israeli-backed mechanism for allowing the distribution of humanitarian help, he said. Israel has been criticized for its decision more than two months ago to block all humanitarian aid, including food, medicine and fuel, the effect of which has been “catastrophic,” doctors say. Israel has argued that the blockade of aid is lawful and that Gaza still has enough available provisions.

Two reservists who spoke on condition of anonymity because they were not authorized to make comments to the news media said that they had received call-up orders beginning in June.

Eli Cohen, Israel’s energy minister and a member of the security cabinet, said that the reservists were called up in order to implement a plan that would ensure Hamas could never again launch attacks against Israel.

“The destruction of the terrorist organization Hamas is not only an Israeli interest but also an interest of the entire free world,” he said, adding that “the cabinet unanimously decided to expand the operation in Gaza and move now toward defeating Hamas.”

The question is whether a return to that kind of fighting is a road map to the end of hostilities or merely an intensification of a deadly conflict with worsening consequences for Palestinians and the Israeli hostages still being held by Hamas.

Tamir Hayman, who served as the Israeli military’s intelligence chief for four years, said the attempts to pressure Hamas with overwhelming force had been “exhausted” after more than a year and a half of war.

“Eliminating Hamas as a terror organization by military force only is very difficult,” said Mr. Hayman, who is now executive director of the Institute for National Security Studies, a think tank in Tel Aviv. He said Israel would be better off ending the war with Hamas, which has been weakened significantly and can be kept in check after the fighting ends.

The Israeli military has not provided details about how the reservists will be deployed. But two Israeli officials, who requested anonymity to comment on military plans, say it will involve several brigades seeking so-called operational superiority in several parts of Gaza.

The Trump administration has sought a new cease-fire, but Hamas has demanded an end to the war and a withdrawal of Israeli forces from Gaza, while Israel has insisted that Hamas disarm, which the group has refused to do.

Israeli officials have said they believe it was the power and intensity of their military campaign in Gaza last year that pressured Hamas to release some of the hostages and to accept a cease-fire in January.

Hours after the October 2023 attacks, Mr. Netanyahu ordered the mobilization of 360,000 reservists, adding to the country’s standing military of about 170,000 soldiers.

In the fighting since, more than 50,000 Palestinians have died, according to the Gaza health ministry, which does not distinguish between civilian and military deaths. About 130 hostages have been released and the Israeli military has retrieved the bodies of at least 40 others. Around 24 hostages are thought to be still alive, according to the Israeli government.

Awad Abid, a 38-year-old resident of Jabaliya in northern Gaza, said the Israeli announcements had brought on further despair among the enclave’s Palestinian residents. The monthslong blockade on humanitarian had caused “hunger to enter every house,” he said.

“There’s no more life here for anyone in Gaza,” Mr. Abid said, adding that the Israeli hostages should be released immediately to end to the conflict.

When Israel and Hamas agreed to the January cease-fire deal, Mr. Netanyahu said credit should go to the “painful blows that our heroic fighters have landed on Hamas.”

“This is exactly how the conditions were created for the turning point in its position and for the release of our hostages,” he said during a national address.

But other voices, like Yair Lapid, Israel’s opposition leader, have expressed grave doubts about the strategy. “I fear that the intensity of the fighting will dictate the fate of the hostages,” Mr. Lapid said on Israeli Army Radio. “What is the goal? Why are they calling up reservists? Extending regular service and all without defining a goal — that’s not how you win a war.”

In a statement Monday, the organization representing the families of hostages urged the government not to widen the war.

“The expansion of military operations puts every hostage at grave risk,” the families said. “We implore our decision makers: Prioritize the hostages. Secure a deal. Bring them home — before it’s too late.”

Natan Odenheimer, Johnatan Reiss and Gabby Sobelman contributed reporting.