The Biden administration is preparing for the possibility that hundreds of thousands of American citizens will require evacuation from the Middle East if the bloodshed in Gaza cannot be contained, according to four officials familiar with the U.S. government’s contingency planning.

The specter of such an operation comes as Israeli forces, aided by U.S. weapons and military advisers, prepare for what is widely expected to be a perilous ground offensive against Hamas militants responsible for the stunning cross-border attack that has reignited hostilities. The officials, speaking on the condition of anonymity to detail internal deliberations, said Americans living in Israel and neighboring Lebanon are of particular concern, though they stressed that an evacuation of that magnitude is considered a worst-case scenario and that other outcomes are seen as more likely.

Still, one official said, it “would be irresponsible not to have a plan for everything.”

The administration, despite its forceful public support for Israel, is deeply alarmed by the prospect of escalation, and in recent days it has turned its attention in part to the complicated logistics of abruptly having to relocate a large number of people, according to three people familiar with the discussions. There were about 600,000 U.S. citizens in Israel and another 86,000 believed to be in Lebanon when Hamas attacked, according to State Department estimates.

The concern in Lebanon is chiefly over Hezbollah, a political party and militant group that has controlled the country since 1992. It has long accepted training and weapons from Iran, prompting concerns that it could attack Israel from the north, creating a two-front war that would stretch Israeli forces. Already, there have been skirmishes along their shared border.

“This has become a real issue,” one official said. “The administration is very, very, very worried that this thing is going to get out of hand.”

The administration’s concern extends beyond those two countries, as officials watch the street protests that have spread across the Arab world, putting both U.S. personnel and citizens in the region at heightened risk. The bombardment of Gaza has inflamed regional fury at Israel and its treatment of Palestinians — an issue some officials believed no longer carried as much importance in the Arab world.

“The street to a large extent is now in charge,” said Bruce Riedel, a senior fellow at the Brookings Institution and former official in the Clinton administration.

“We were told for the last 10 years that the Arab world and Muslim world didn’t care about Palestine anymore, and Abraham Accords were proof of that,” Riedel added, referring to agreements, signed by the governments of Sudan, Morocco, Bahrain and the United Arab Emirates, aimed at normalizing relations with Israel. “Well, Palestine has come back. I don’t think it ever went away.”

More than 5,000 people in Gaza, mostly civilians and children, have been killed amid unrelenting Israeli airstrikes since the Oct. 7 attacks, Palestinian health officials say.

Top U.S. officials have not wanted to discuss such contingency planning in public, hoping to avoid setting off a panic among Americans in the region. But their posture has shifted in recent days to convey the anxiety about other actors entering the conflict.

Last week, the State Department issued an advisory to all U.S. citizens worldwide “to exercise increased caution” due to “increased tensions in various locations around the world, the potential for terrorist attacks, (and) demonstrations or violent actions against U.S. citizens and interests.”

The warning was in response to demonstrations that have erupted in response to the Israel-Hamas conflict and broader anger in the Arab world over Washington’s full political, economic and military backing of Israel.

Depending on the scale of a potential U.S. evacuation, it could be more difficult than any previous operations in recent memory, experts said. It could involve Air Force aircraft or Navy warships, which have surged to the region this month.

“With 600,000 Americans in Israel and threats to other Americans across the region, it’s hard to think of an evacuation that might compare to this in scale, scope and complexity,” said Suzanne Maloney, the director of foreign policy at the Brookings Institution.

“The sort of advisories the State Department has put out lately have been fairly blunt,” she added.

On Monday, the Pentagon signaled, too, that it is bracing for a significant increase in attacks on U.S. troops in the Middle East, and the department singled out Iran for its extensive sponsorship of militant groups with a long history of using rockets and drones to target American military positions. In response, Pentagon officials said, they are surging additional missile-defense systems to the region.

Brig. Gen. Patrick Ryder, a Pentagon spokesman, told reporters that a “broader escalation” is possible “in the days ahead.” Senior military leaders, he said, are taking “all necessary measures” to safeguard U.S. personnel.

Particularly vulnerable are the estimated 3,400 troops deployed in Iraq and Syria, where earlier in the day U.S. personnel based near the Jordan border intercepted at least two one-way attack drones, officials said. Americans operating in those countries have been targeted for years by Iranian-backed militias, including Kataib Hezbollah, an Iraq-based group that claimed responsibility for some of the previous attacks disclosed over the last week.

“We don’t necessarily see that Iran has explicitly ordered them to take these kinds of attacks,” Ryder said. “That said, by virtue of the fact that they are supported by Iran, we will ultimately hold Iran responsible.”

It’s unclear how many times deployed personnel have come under fire since the Israel-Hamas crisis began Oct. 7. Officials said that the Pentagon was compiling a list of confirmed incidents but that the effort had been hampered by what one senior defense official called the profusion of “disinformation and misinformation.”

No U.S. personnel are known to have been killed or seriously injured in any of the spillover violence. An American contractor in Iraq did suffer a fatal heart attack last week as troops and others at the Ain al-Asad air base raced to take cover from what proved to be a false alarm of an incoming attack.

Sarah Dadouch in Beirut and Missy Ryan contributed to this report.

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