Israel-Gaza updates: Biden speaks with Netanyahu about hostages' release, Gaza humanitarian assistance

United Nations experts said they're urging the lawyers advising Israeli forces "to refuse legal authorisation for acts that may amount to war crimes."

The lawyers' "advice about issues such as lawful targets of attack, the choice and use of weapons, and the means and methods of warfare is essential to the operational planning of military campaigns," the U.N. experts said in a statement Monday.

"Under international law, Israel has a right to self-defence, but its response must be proportionate and in full respect of the UN Charter and the rules that apply to the use of force in armed conflict," the experts said.

"If such lawyers approve actions that amount to massive human rights violations and war crimes, they may bear accomplice liability for those acts," the experts warned.

Twenty aid trucks crossed from Egypt to Gaza through the Rafah border crossing on Monday, according to the United Nations.

The Rafah border crossing was shut on Oct. 10 after it was hit by Israeli warplanes on the Palestinian side three times on Oct. 9 and 10.

After nearly two weeks of humanitarian conditions worsening by the day, the crossing briefly opened on Oct. 21 and Oct. 22, permitting a small amount of aid to enter Gaza. The U.N. said 34 trucks entered this weekend.

Stéphane Dujarric, spokesman for the U.N. secretary-general, called this only "a drop in the bucket."

"The number of trucks that usually went into Gaza every day was about 450 or so, and now we're seeing 20 or 30, and we're not seeing any fuel, which is a great concern," Dujarric said. "For the 14th consecutive day, Gaza remains under a full electricity blackout. The situation in hospital remains dire given the shortage of electricity, medicine, equipment and specialized personnel."

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US citizen trapped in Gaza speaks out on his experience Abood Okal, a 36-year-old American, has been stranded in Gaza with his wife and 1-year-old son since the beginning of the war.

ABCNews.com

Images of Israel's potential ground invasion into Gaza could serve as "a catalyst for various violent actors," the Department of Homeland Security warned in an intelligence assessment on Sunday.

The agency said it's "concerned about lone offenders inspired by or responding to the conflict committing simple, unsophisticated attacks that are difficult to warn of in advance."

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Israel's defense minister says military campaign in Gaza may take months Issa Amro, a Palestinian human rights activist in the West Bank, breaks down what he’s seeing.

ABCNews.com

"Some individuals continue to call for violence against Jewish, Muslim, and Arab targets in the United States across various social media platforms," the assessment said. "We continue to be concerned about threats to houses of worship and other institutions."

Domestic extremists, while a concern, have not signaled any "intent to provide facilitation or assistance to any foreign terrorist organizations in the Gulf region, including HAMAS or Hezbollah," the assessment said.

-ABC News' Luke Barr

Israeli forces are "preparing thoroughly for the next step -- a multilateral operation in the air, ground and sea," Israeli Defense Minister Yoav Gallant said Monday.

To the soldiers, Gallant said in Hebrew, "Keep preparing for our operation, it will come soon."

"Do your work, get ready," he said. "We will need you.”