Israel-Gaza live updates: 6 UN workers killed in strike on Gaza school

The White House is remaining hopeful that talks for a cease-fire in Gaza and release of the remaining hostages can be salvaged after Hamas proposed new amendments to the deal following the killing of six hostages.

"Hamas did change some of the terms of the exchange. And that has made it more difficult for us to get there," National Security Communications Adviser John Kirby said at Monday’s press briefing.

"We still believe that, even for the new amendments that Hamas has made, that it's still worth an effort to try to see if we can't get back into a cease-fire negotiation," he added. "But we're not there right now."

Kirby would not say if President Joe Biden will be increasing pressure on Israeli Prime Minister Benjamin Netanyahu to accept a deal and potentially hold the transfer of weapons to Israel in order to secure a deal, similar to the recent decision by the United Kingdom.

"I can't think of anything we haven't put more pressure on ourselves than to try to get this deal," Kirby said. "We know how urgent this is. And we're working night and day to try to see if we can get a deal in place. Hamas is the main obstacle to this right now."

-ABC News' Justin Ryan Gomez

The commander of U.S. Central Command was presented with Israel Defense Forces (IDF) "operational plans for Lebanon" during his weekend visit, the IDF said.

Gen. Michael Kurilla met with the Chief of Israel's General Staff Lt. Gen. Herzi Halevi for a "situational assessment" and visited the Northern Command, which is responsible for the frontiers with Lebanon and Syria.

The general's visit had "an emphasis on threats from Lebanon and Iran in the northern arena," the IDF wrote on social media.

Kurilla met with Maj. Gen. Ori Gordin -- Northern Command's commanding officer -- "conducted a situational assessment in the command's underground operations center and received an operational briefing, during which he was presented with the IDF's operational plans for Lebanon," the force said.

Cross border skirmishes between the IDF and Hezbollah -- which is aligned with Iran -- have been near constant since Oct. 8, 2023, the uptick in fighting prompted by Hamas' Oct. 7 attack on southern Israel and the subsequent IDF response.

Israeli leaders have threatened a significant military operation into southern Lebanon unless Hezbollah withdraws its forces north of the Litani River, some 18 miles north of the shared border.

-ABC News' Jordana Miller and David Brennan

The Israel Defense Forces (IDF) reported "a hostile aircraft infiltration" in the north of the country on Monday morning.

"Two suspicious aerial targets were identified crossing from Lebanon into Israeli territory," The IDF said in a statement. "An aerial target fell in the area of Nahariya. No injuries were reported."

The Magen David Adom (MDA) -- Israel's emergency services -- said in a social media post that its personnel "located the site of the impact, as of now no casualties have been found."

Israeli media reported that a drone detonated after crashing into an apartment block.

-ABC News' Dana Savir and David Brennan

The Hostages Families Forum Headquarters organized twin protests in Tel Aviv and New York on Sunday, as pro-cease-fire activists look to build pressure on Prime Minister Benjamin Netanyahu's government and American politicians.

Hundreds of people rallied in Central Park "to mourn six Israeli and American hostages murdered after 11 months in captivity," the Forum said in a press release.

Among the speakers were Gilad and Nitza Korngold -- the parents of hostage Tal Shoham who was abducted into Gaza on Oct. 7.

"The Red Cross has refused to help our loved ones while shamelessly requesting better conditions for the terrorists in Israel's imprisonment," they said, per the Forum's press release. "We ask everyone here to call your representatives and demand the release of our loved ones from captivity."

Moran Stela Yanai -- released in November 2023 after 54 days as a hostage in Gaza -- also spoke, telling attendees: "My brothers and sisters in captivity are hungry and in pain and in constant danger."

"We must find the strength to keep fighting for them and bring them home," she added, as quoted in the Forum's press release.

-ABC News' Jordana Miller and David Brennan