ABC News' Ian Pannell speaks to Mark Regev, the advisor to Prime Minister Benjamin Nentayahu and a former ambassador, on Israel's expanded ground operation in Gaza. Regev said the land operation could be long, with many challenges.

"We are continuing to beef up the pressure on Hamas," said Regev. "It will continue to rise in the coming days and weeks until we achieve our goal which is the total dismantlement of the Hamas military machine and the end of their political structure in Gaza."

In a press briefing on Saturday, Israeli military spokesman Rear Adm. Daniel Hagari said that "the forces are still on the ground and are continuing the war" and the Israel Defense Forces "will continue to make a concerted effort in order to maintain the security of our forces, using strong fire from the air, this is combat."

Meanwhile, several Hamas commanders have been killed overnight as part of the expanded offensive as aid trucks make their way into Gaza carrying food and water.

Hagari confirmed there have been 311 Israel Defense Forces fatalities since Oct.7 and added that the IDF have suffered no casualties in the overnight operations.

There are reports that communication networks have been cut in Gaza and WHO Chief Tedros Ghebreyesus who said the communications blackout is making it “impossible to reach the injured” and WHO staff, according to a statement posted on X (formerly Twitter).

The Israel Defense Forces said they hit 150 underground targets in the northern Gaza Strip overnight and killed the head of Hamas’ Ariel Array – Asem Abu Rakaba.

In a Saturday morning post, the IDF said that based on intelligence it had and intelligence from the Israel Securities Authority, IDF fighter jets struck and killed Abu Rakaba.

He was responsible for Hamas' UAVs, drones, paragliders, aerial detection and aerial defense, the IDF and Israel Securities Authority said in a joint release. He took part in planning the massacre in the communities surrounding the Gaza Strip on Oct. 7, the IDF said. He directed the terrorists who infiltrated Israel on paragliders and was responsible for the drone attacks on IDF posts, according to the military.

The IDF said it also hit tunnels and underground infrastructure. Several Hamas terrorists were killed in the attacks, according to the IDF.

-ABC News’ Clark Bentson

Protesters with a Jewish peace activist group are calling for an immediate cease-fire in Gaza in a large, ongoing demonstration Friday at Grand Central Terminal in New York City.

Metro-North said Grand Central is closed due to the protest.

According to organizer Jewish Voice for Peace-New York City, a far-left Jewish group, thousands of members and allies are taking part in the sit-in, which comes after Israel announced it is expanding its ground activity in Gaza.

Israel's expanding ground assault on Gaza will involve months of painstaking and "very fierce fighting" with Hamas extremists amid conditions "unlike anything that we’ve seen in recent years," retired Army Gen. Robert Abrams predicted on Sunday.

"And simultaneously trying to ensure that the Israelis do not target, unwittingly, the locations on the hostages -- this is going to prove to be a very difficult task," Abrams told ABC "This Week" co-anchor Martha Raddatz. "And we’ll just have to see how their plan plays out here over the coming days."

Abrams, who commanded U.S. troops during America's invasion of Afghanistan and Iraq, went on to say that he believes Israeli forces face a nigh insurmountable challenge in their stated goal to destroy the militant group that launched a terror attack on Israel earlier this month -- while seeking to limit civilian casualties in the Palestinian territory and recover the hundreds of captives Hamas is thought to be holding in Gaza.

"It’s going to be what I would consider nearly impossible to destroy Hamas, to eliminate their capability to do harm to Israel and the Israeli people, while simultaneously protecting what some people have estimated as to be a million Palestinians who are in harm’s way and they can’t get out of harm’s way," Abrams said.

Israel has faced mounting international outcry at the potential humanitarian disaster in the blockaded territory as it carries out its retaliatory operations on the militants.

Abrams said on "This Week" that he thinks "every effort is being made to follow the laws of armed conflict" but acknowledged the "horrific" images being broadcast of the escalating conflict.

"Fundamentally, at the end of this, Martha ... we still have to answer the question: What is the future? Hamas was created as a result of a lack of a separate Palestinian state. A two-state solution, as many people have talked about. That has to be somewhere, when you asked, 'How does this end?' That has to be part of the equation," Abrams said.

-ABC News' Adam Carlson