Israel-Gaza live updates: Israeli officials on reports of Russian airport protesters

Securing the release of the hostages being held in Gaza is still a priority as Israel expands its ground assault in the territory in an effort to defeat Hamas, the White House's national security adviser said Sunday.

"We are continuing to see if there are ways to make that happen. We are prepared to support humanitarian pauses so that hostages can get out safely. And we will keep working at that every day because the president has no higher priority than the safe return of American citizens and wants to support the return of citizens of other countries and Israelis, as well," Jake Sullivan told ABC "This Week" co-anchor Martha Raddatz.

"Now, how exactly that happens ... I cannot predict that. All I can tell you is every effort is being undertaken right now to do that," Sullivan said.

But he noted "there are ongoing efforts which I can't get into detail on television, including regional partners, including the Israelis."

-ABC News' Tal Axelrod

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US is ‘prepared to support humanitarian pauses’ to free hostages: Jake Sullivan

ABC News’ Martha Raddatz interviews National Security Adviser Jake Sullivan on “This Week.”

ABCNews.com

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.

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Israeli ground incursion will ‘take a long time’: Gen. Robert Abrams

ABC News’ Martha Raddatz interviews retired Gen. Robert Abrams on “This Week.”

ABCNews.com

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

The number of people believed to have been taken hostage by Hamas during the Oct. 7 terror attack on Israel has risen to 230, according to Israel Defense Forces spokesman Rear Adm. Daniel Hagari.

During a press briefing on Sunday morning, Hagari said bringing the hostages home remains a top priority and that Israeli forces on the ground in the neighboring Gaza Strip are working to achieve this goal.

The IDF expanded its entry of troops into Gaza overnight, joining the forces already fighting on the ground there, according to Hagari.

"We are gradually expanding the ground activity and the scope of our forces in the Gaza Strip," Hagari said. "The operations on the ground are complex and include risks to our forces."

Over the past 24 hours, the IDF struck 450 Hamas military targets in Gaza. Ground forces directed IDF aircraft toward the targets and also struck "terrorist cells" that attempted to attack them, according to Hagari.

The IDF also struck Hezbollah military positions in neighboring Lebanon in response to attacks on IDF positions, Hagari said.

The IDF will draft new soldiers in November as was scheduled, even during the war, according to Hagari.

-ABC News' Anna Burd, Bruno Nota and Morgan Winsor

The United Nations Relief and Works Agency said Sunday that "thousands of people" have broken into several of their warehouses and distribution centers in the middle and southern parts of the Gaza Strip, "taking wheat flour and other basic survival items like hygiene supplies."

"This is a worrying sign that civil order is starting to break down after three weeks of war and a tight siege on Gaza," Thomas White, director of UNRWA affairs in Gaza, said in a statement. "People are scared, frustrated and desperate. Tensions and fear are made worse by the cuts in the phones and internet communication lines. They feel that they are on their own, cut off from their families inside Gaza and the rest of the world."

Since Oct. 7, a "massive displacement of people" who were forced to leave the north of Gaza and head southward due to Israeli airstrikes "has placed enormous pressure on those communities," according to UNRWA.

"Supplies on the market are running out while the humanitarian aid coming into the Gaza Strip on trucks from Egypt is insufficient," White added. "The needs of the communities are immense, if only for basic survival, while the aid we receive is meager and inconsistent."

As of Sunday morning, just over 80 trucks of humanitarian aid had crossed into Gaza from Egypt in one week. There was no aid delivered on Saturday due to a communications blackout in Gaza, according to UNRWA. The agency, which is the main actor for the reception and storage of aid in Gaza, said it was "not able to communicate with the different parties to coordinate the passage of the convoy."

UNRWA said its teams in Gaza have reported that internet services and connections were restored. The agency said it will reassess the situation with the goal of resuming aid convoys and distribution on Sunday.

"The current system of convoys is geared to fail," White said. "Very few trucks, slow processes, strict inspections, supplies that do not match the requirements of UNRWA and the other aid organizations, and mostly the ongoing ban on fuel, are all a recipe for a failed system. We call for a regular and steady flow line of humanitarian supplies into the Gaza Strip to respond to the needs especially as tensions and frustrations grow."

Meanwhile, UNRWA said 59 staff members have now been killed in Gaza since Oct. 7.

-ABC News' Guy Davies and Morgan Winsor