Israeli Ground Forces Seize Part of Gaza Corridor, Raising Pressure on Hamas

Israeli ground forces pushed deeper into the Gaza Strip on Wednesday, taking over part of a major corridor that bisects the Palestinian enclave, in the most significant ground operation since the collapse of the cease-fire with Hamas.

The operation followed wide-scale Israeli aerial bombardment in Gaza that began early on Tuesday morning, ending the fragile truce that had held since mid-January. More than 400 people were killed in the airstrikes, according to the Gaza health ministry, which does not distinguish between civilians and combatants.

On Wednesday, the Israeli military said soldiers had begun “targeted ground activities” along the road — known as the Netzarim Corridor — to create a “partial buffer zone” between northern and southern Gaza. Israeli forces had widened their control “to the center of the Netzarim Corridor,” the military said.

Israel has not returned to full-scale war in Gaza that matches the intensity of its 15-month military campaign against Hamas. The Palestinian armed group has also not responded militarily to the Tuesday attack, which it said killed at least five members of its Gaza leadership.

It was unclear how many Israeli soldiers were now deployed along the part of the Netzarim Corridor or whether it marked the beginning of a sustained ground offensive. But Israeli leaders appeared to be gradually stepping up attacks, in an apparent effort to force Hamas to agree to more favorable terms for a settlement to free the dozens of hostages remaining in Gaza.

And unless Hamas capitulated, Israel was ready to continue ramping up pressure on the group, officials said.

Israel Katz, the Israeli defense minister, threatened Wednesday that Israel could again start ordering Palestinians to flee parts of Gaza that had become combat zones, as it frequently did before the cease-fire.

“What comes next will be much harder, and you will pay the full price,” Mr. Katz said in a video statement addressing Palestinians in Gaza.

But analysts said that it was far from clear that escalating Israeli military pressure could force Hamas to change its position in the cease-fire talks in the short term. Hamas has vowed that Israel will not “achieve through war in destruction” what it failed to force the group to accept at the negotiating table.

Control of the Netzarim Corridor allowed the Israeli military to prevent hundreds of thousands of Palestinians displaced to the south from returning to their homes in northern Gaza. At least one major route along the coast still appeared to be outside of Israeli control as of Wednesday, allowing Palestinians to travel across the enclave.

During the war, Israeli soldiers fortified the road, building up a network of outposts and bases. They also leveled hundreds of buildings for miles around, giving them a clear line of sight, and funneled those allowed to cross through military checkpoints.

After the cease-fire with Hamas went into effect in January, Israel gradually withdrew from the Netzarim Corridor, although they remained deployed in a buffer zone inside Gaza and along the enclave’s border with Egypt. Palestinians returned home en masse in emotional scenes, often finding little but rubble where their homes and neighborhoods once stood.

Before the Israeli attack, mediators were seeking to broker an agreement between Israel and Hamas on the next steps in the cease-fire. Under the terms of the deal, the second phase is supposed to include an end to the war, the full withdrawal of Israeli forces and the release of the remaining living hostages in Gaza.

But neither side would accommodate the other’s demands. Israel was unwilling to end the war as long as Hamas remained in power in Gaza. Hamas refused to disband its armed battalions, send its leaders in Gaza into exile or release many more hostages unless Israel committed to permanently halting its campaign.

The first phase of the deal elapsed in early March. Almost immediately, Israel mostly shut off Gaza’s border crossings to humanitarian aid, preventing food, medicine and other supplies from entering the enclave. Later, the Israeli government cut off electricity it provided to a desalination plant in central Gaza.

Finally, on Tuesday, the Israeli surprise attack effectively shattered what remained of the fragile cease-fire. Israeli fighter jets bombarded sites across the Gaza Strip in an intense assault; the Israeli military said it was targeting Hamas operatives and sites.

The pace of the bombing later slowed, although Israeli fighter jets continued striking across Gaza on Wednesday.

Miri Eisin, a retired Israeli colonel, said Israel was still escalating relatively slowly, given both the timing — the Muslim holy month of Ramadan — and hopes for an agreement to get more hostages out in the meantime.

“You couldn’t leave it in limbo — that would be Hamas defining the rules of the game,” said Ms. Eisin, a senior fellow at the International Institute for Counter-Terrorism, an Israel-based research organization.

But she added that Israel’s military actions thus far seemed unlikely to influence “the portions of Hamas who hold the hostages,” she said, referring to Hamas’s military leaders in Gaza.

Separately, the United Nations said one of its officers was killed and five others seriously injured in strikes on two compounds where they were staying in central Gaza. The Israeli military denied any connection to strikes on the compound. U.N. officials did not say who or what was behind the explosions.

“The locations of all U.N. premises are known to the parties to the conflict, who are bound by international law to protect them and maintain their absolute inviolability,” said Farhan Haq, a spokesman for the U.N. secretary general.

Johnatan Reiss contributed reporting from Tel Aviv.