The Israeli military has razed block after block of Gaza City as part of a new ground offensive in what was once the territory's largest urban center.

Israel's war against Hamas, which began two years ago, has leveled wide swathes of the Gaza Strip, including the city of Rafah in the south and the town of Beit Hanoun in the north. But the military did not carry out such widespread demolitions in previous Gaza City operations.

This time is different.

Though much of the city is still standing, satellite images show Israeli forces are destroying whole areas as they sweep into Gaza City, including the Zeitoun neighborhood and an area near Sheikh Radwan, where the military has demolished dozens of structures this month.

Previously, Israeli troops advanced through Gaza City and then withdrew - only to return later to fight what they said was a renewed Hamas insurgency. Prime Minister Benjamin Netanyahu of Israel said this time around was different because the military would hold areas it seized.

"We capture territory and we hold it. We clean it out and we move forward," he said in an interview this month with Channel 14, a right-wing Israeli television station.

Mr. Netanyahu says the offensive aims to decisively rout Hamas from one of its last strongholds in the Gaza Strip. But even many Israelis are skeptical that this strategy will succeed now, as Hamas has proven resilient in the face of nearly two years of devastating war.

The Israeli ground offensive has forced hundreds of thousands of Palestinians to flee their homes in Gaza City, crowding into swelling tent camps in central and southern Gaza.

This has exacerbated what was already a humanitarian catastrophe in Gaza, with rampant hunger, mass displacement and a collapse of health care, schools and infrastructure. Many war-weary Gaza City residents say they simply cannot or will not be displaced again, and many have no homes to return to.

While closing in on Gaza City, Israel has used existing buildings as bases, only to later destroy them with explosives before moving onward, according to satellite images and videos verified by The New York Times.

One video shows the military destroying Al-Furqan school in the city, which it had earlier used as a military position.

In addition to carrying out demolitions, the Israeli military has also kept up airstrikes across Gaza City, striking hundreds of targets since mid-September.

In a satellite image from Sept. 18, the latest high-resolution image available from Planet Labs, a commercial satellite company, fewer tents could be seen compared with a time before Israel announced the launch of its Gaza City ground offensive two days earlier. Still, hundreds of tents were visible, many within around a mile of Israeli military vehicles.

Mustafa Siyam, 44, said he finally fled the city's northern Shati neighborhood on Wednesday as Israeli forces drew nearer and the sound of explosions became incessant. He walked south for hours on foot with his wife and three children to reach central Gaza.

Mr. Siyam's home was still standing before the current Israeli offensive. That might not be the case by the time he returns.

"It feels like the war has no goal or meaning, except to destroy as much of Gaza's foundations as possible," he said.

Israeli military officials have told reporters there is no policy to raze civilian neighborhoods wholesale. They say they are attacking sites used by Hamas, blowing up underground tunnels and other military targets.

But Israeli leaders have suggested it could go further than that.

Israel Katz, the defense minister, threatened in August that Gaza City would become "like Rafah and Beit Hanoun," two cities that have been almost entirely destroyed in the war, unless Hamas laid down its arms and released the remaining hostages.

Eli Cohen, another minister in the high-level security cabinet, echoed the threat in a television interview, telling Channel 14 that "Gaza City itself should be exactly like Rafah, which we turned into a city of ruins."

Israel Is Flattening Areas of Gaza City