Israel-Gaza updates: Biden speaks with Netanyahu about hostages, Gaza aid

The Israeli military has a "green light" to move into Gaza whenever it's ready, a member of the country’s security cabinet told ABC News.

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Israeli military has 'green light' to move into Gaza, official saysThe Israeli military has a “green light” to move into Gaza whenever it's ready, a member of the country’s security cabinet told ABC News.

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Hostages and civilian casualties will be secondary to destroying Hamas, Economy Minister Nir Barakat told ABC News, "even if it takes a year."

Asked about the miles of tunnels Hamas has built under Gaza, he said they’d become the "world’s biggest cemetery." Hamas has claimed to be holding some or all of the 203 Israeli hostages it’s taken within that vast network.

"We shall do all efforts to bring our hostages, to bring our hostages [back] alive…" he said, but the "first and last priority" is destroying Hamas.

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Warfare expert calls Hamas tunnels ‘a major threat to civilians on both sides’ABC News’ Linsey Davis spoke with warfare expert and Reichman University Assistant Professor Daphné Richemond-Barak about the intricate Hamas tunnel system in Gaza.

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Hamas and Islamic Jihad together have about 50,000 fighters, said Agriculture Minister Avi Dichter, former head of Shin Bet, the Israel Security Agency.

-ABC News’ Matt Gutman

The State Department on Thursday issued a bulletin for "worldwide caution" because of "increased tensions" around the world and "the potential for terrorist attacks, demonstrations or violent actions."

The State Department warned that Americans abroad should stay alert, enroll in the Smart Traveler Enrollment Program and follow the State Department on social media.

The State Department is instructing its embassies and consulates around the world to conduct emergency security reviews amid ongoing protests sparked by the Israel-Hamas war, according to sources familiar with the matter and documents reviewed by ABC News.

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Protests turn violent in Lebanon Protests have erupted in Lebanon outside the French Embassy and a United Nations facility.

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Secretary of State Antony Blinken also instructed personnel to evaluate whether embassies should issue alerts to Americans in their respective countries about threats posed by the demonstrations, as many have already done.

A number of posts have asked the State Department to modify their operations due to security concerns, sources said, but at this point it does not appear that any additional embassies have asked to go on authorized departure, and so far none have requested a full evacuation.

-ABC News' Shannon Crawford

Israel has blamed Palestinian Islamic Jihad for Tuesday night's deadly blast at a Gaza hospital.

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What is Palestinian Islamic Jihad? The radical Islamist movement was founded in 1980 by Palestinian Fathi Shaqaqi.

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Like Hamas, Palestinian Islamic Jihad is a Gaza militant group involved in the conflict and has claimed to have taken Israelis hostages.

Click here to read what you need to know about the group.

At least 3,785 people have been killed in Gaza, including 1,524 children, 1,000 women and 120 elderly people, according to the Gaza Health Ministry.