The State Department has raised its travel advisory level for Israel and the West Bank to "level 3 -- reconsider travel" due to terrorism and civil unrest.

"Terrorist groups, lone-actor terrorists and other violent extremists continue plotting possible attacks in Israel and the West Bank and Gaza," an alert from the department states. "Terrorists and violent extremists may attack with little or no warning, targeting tourist locations, transportation hubs, markets/shopping malls, and local government facilities."

Both regions were previously at "level 2 -- exercise increased caution."

The advisory also adds increased restrictions for U.S. government employees, declaring they can only travel to Israel for "mission-critical travel."

Gaza remains at "level 4 -- do not travel."

-ABC News' Shannon K. Crawford

President Joe Biden spoke with United Arab Emirates President Mohamed bin Zayed Wednesday to discuss the attacks in Israel, stressing his condemnation of Hamas’ brutality, according a White House readout of the call.

The two leaders also discussed ensuring humanitarian assistance for those in need and Biden's warnings against countries and organizations who may exploit the situation, according to the readout.

-ABC News' Justin Gomez

President Joe Biden said at a roundtable with Jewish leaders on Wednesday that the U.S. is "doing a lot" to rescue the Americans held hostage by Hamas.

"We're working on every aspect of the hostage crisis in Israel, including deploying experts to advise and assist with recovery efforts," he said. "I have not given up hope of bringing these folks home."

Second Gentleman Doug Emhoff also delivered remarks at the roundtable. Emhoff, the first Jewish spouse of a president or vice president, said, "Like all Jews, I feel a deep visceral connection to Israel and its people."

"We witnessed a mass murder of innocent civilians," he said. "The images that we saw will be seared in our brains forever. Rockets falling on cities, people dragged from their homes and shot dead, children sheltering from bullets, bodies lining the streets. And all the while, we see videos of these terrorists cheering on these atrocities. "

"I know you're all hurting. The entire Jewish community is hurting, I'm hurting," he said.

The State Department said it's "exploring contract options" to help Americans looking to leave Israel travel to nearby countries.

Though there are still commercial flights available from Israel, they are limited, the State Department noted.

An official familiar with the discussions said the State Department may bring in charter flights to get Americans from Israel to nearby countries where they can then take commercial flights to the U.S.

A separate State Department spokesperson said the administration was "acutely aware of the currently limited capacity on commercial flights and the high demand from U.S. citizens wanting to depart," and said that for now, Americans should "take advantage of commercial flights that involve transiting a third country if they are unable to book a direct flight to the United States."

-ABC News' Shannon Crawford

Human Rights Watch has accused Israel of using white phosphorus munitions in military operations in Gaza on Wednesday, saying it violated international humanitarian law by putting civilians at unnecessary risk.

In a report released Thursday, Human Rights Watch said it based its determination on a video it said it has verified, as well as two eyewitness accounts.

The Israel Defense Forces said in a statement to ABC News that claims they used white phosphorus in Gaza are "unequivocally false."

ABC News geolocated a video showing a jellyfish-shaped plume of white smoke over the port of Gaza. The video was posted on Wednesday by the official Palestinian news agency WAFA and matches images posted on social media and by other news outlets on the day.

Two experts -- Amael Kotlarski, the weapons team manager for the defense intelligence firm Janes, and Amnesty International weapons investigator Brian Castner -- told ABC News that images suggested munitions deployed over the port of Gaza on Wednesday appeared to contain white phosphorus.

"We have verified that Israeli artillery forces striking Gaza are equipped with M825 and M825A1155mm white phosphorus projectiles," Castner told ABC News, pointing to photographs by an Anadolu Agency photographer taken on Monday and showing Israeli troops handling shells labeled "M825A1."

Kotlarski said visual evidence alone was not sufficient to confirm that these specific shells were used in the Gaza port strikes.

There are "perfectly legal" military uses for white phosphorus munitions, Kotlarski said, including to create a smoke screen to conceal movements, to mark targets for artillery or air strikes, or to illuminate a battlefield. However, its use in urban areas is "problematic due to the higher risk of collateral damage," Kotlarski said, including the munitions' potential to cause severe burns.

White House Principal Deputy Press Secretary Olivia Dalton said Friday the U.S. had not independently verified allegations Israel used white phosphorous "so that is not something I would want to speculate about or weigh in on at this time."

-ABC News' Christopher Looft, Ben Gittleson and Jordana Miller