JERUSALEM (AP) — The Israeli military on Wednesday said it had uncovered a major Hamas command centre in the heart of Gaza City, inflicting what it described as a serious blow to the Islamic militant group as pressure grows on Israel to scale back its devastating military offensive in the coastal enclave.

The army said it had exposed the centre of a vast underground network used by Hamas to move weapons, militants and supplies throughout the Gaza Strip. Israel has said destroying the tunnels is a major objective of the offensive.

The announcement came as Hamas’ top leader arrived in Egypt for talks aimed at brokering a temporary cease-fire and a new deal for Hamas to swap Israeli hostages for Palestinians imprisoned by Israel.

Israeli leaders have vowed to press ahead with the two-month-old offensive, launched in response to a bloody cross-border attack by Hamas in October that killed some 1,200 people and saw 240 others taken hostage.

The offensive has devastated much of northern Gaza, killed nearly 20,000 Palestinians, and driven some 1.9 million people — nearly 85 per cent of the population — from their homes. The widespread destruction and heavy civilian death toll has drawn increasing international calls for a cease-fire.

Hamas militants have put up stiff resistance lately against Israeli ground troops, and its forces appear to remain largely intact in southern Gaza. It also continues to fire rockets into Israel every day.

The United States (US), Israel’s closest ally, has continued to support Israel’s right to defend itself while also urging greater effort to protect Gaza’s civilians.

But in some of the toughest American language yet, Secretary of State Antony Blinken on Wednesday called on Israel to scale back its operation.

“It’s clear that the conflict will move and needs to move to a lower intensity phase,” Blinken said. He said the US wants to see “more targeted operations” with smaller levels of forces focused on specific targets, such as Hamas’ leaders and the group’s tunnel network.

“As that happens, I think you’ll see as well, the harm done to civilians also decreases significantly,” he said.

His comments were more pointed than statements by Defense Secretary Lloyd Austin, who in a visit to Israel this week said the U.S. would not dictate any time frames to its ally.

The Israeli military escorted Israeli reporters into Palestine Square in the heart of Gaza City to show off what it described as the centre of Hamas’ tunnel network.

Military commanders boasted that they had uncovered offices, tunnels and elevators used by Hamas’ top leaders. The military released videos of underground offices and claimed to have found a wheelchair belonging to Hamas’ shadowy military commander, Mohammed Deif, who has not been seen in public in years.

The army’s chief spokesman, Rear Adm. Daniel Hagari, said the army had located a vast underground complex. “They all used this infrastructure routinely, during emergencies and also at the beginning of the war on October 7,” he said. He said the tunnels stretched across Gaza and into major hospitals. The claims could not be independently verified.

Hagari also indicated that Israel was winding down its operations in northern Gaza, including Gaza City, where it has been battling Hamas militants for weeks. He said the army had moved into a final remaining Hamas stronghold, the Gaza City neighbourhood of Tufah.

But the army also acknowledged a significant misstep. An investigation into its soldiers’ mistaken shooting of three Israelis held hostage in Gaza found that, five days before the shooting, a military search dog with a body camera had captured audio of them shouting for help in Hebrew.

Hagari said the recording was not reviewed until after the hostages were killed while trying to make themselves known to Israeli forces.

The incident has sparked an uproar in Israel and put pressure on the government to reach a new deal with Hamas. The military chief has said the shooting was against its rules of engagement.

The Israeli military campaign now is largely focused on southern Gaza, where it says Hamas’ leaders are hiding.

“We will continue the war until the end. It will continue until Hamas is destroyed, until victory,” Israeli Prime Minister Benjamin Netanyahu said in a video statement. “Whoever thinks we will stop is detached from reality.”

As Netanyahu vowed to continue the war, there were new signs of progress in cease-fire talks.

Hamas’ top leader, Ismail Haniyeh, travelled to Cairo for talks on the war, part of a flurry of diplomacy. In recent days, top Israeli, American and Qatari officials have also held cease-fire talks.

“These are very serious discussions and negotiations, and we hope that they lead somewhere,” the White House’s national security spokesman, John Kirby, said aboard Air Force One while travelling with President Joe Biden to Wisconsin.

Biden, however, indicated a deal was still a ways off. “There’s no expectation at this point, but we are pushing,” he said. Asked about the rising death toll in Gaza, Biden said: It’s tragic.”

Hamas says no more hostages will be released until the war ends. It is insisting on the release of large numbers of Palestinian prisoners, including high-level militants convicted in deadly attacks, for remaining captives.

Osama Hamdan, a senior Hamas official in Beirut, said the efforts right now are focused on how to “stop this aggression, especially that our enemy now knows that it cannot achieve any of its goals.”

Israel has rejected Hamas’ demands for a mass prisoner release so far. But it has a history of lopsided exchanges for captive Israelis, and the government is under heavy public pressure to bring the hostages home safely.

Egypt, along with Qatar and the US, helped mediate a weeklong cease-fire in November in which Hamas freed over 100 hostages in exchange for Israel’s release of 240 Palestinian prisoners. Hamas and other militants are still holding an estimated 129 captives, though roughly 20 are believed to have died in captivity.