Israel-Gaza updates: Nasser Hospital no longer 'functional,' WHO chief says

National security adviser Jake Sullivan said the White House wants to see a "credible plan" from the Israelis for how they would avoid civilian casualties during a potential military operation in Rafah in southern Gaza, where so many residents have fled for safety.

Sullivan said the Israelis are facing "three realities": They must evacuate more than 1 million people to a safe place; they need to avoid disrupting the flow of humanitarian aid; and they need a "clear answer" to what a potential military operation in Rafah would mean for Egypt, which borders Rafah.

Sullivan also made a point to highlight that Hamas "has to account for itself, as well."

"Hamas is hiding amongst civilians, embedding itself among civilians in ways that also put those civilians at risk. And so, some of the international community's questions and pressure, should be on Hamas," he said.

Israeli Prime Minister Benjamin Netanyahu said Wednesday, "We will fight until complete victory, and this includes a powerful action also in Rafah -- after we allow the civilian population to leave the battle zones."

-ABC News’ Justin Gomez

FBI Director Christopher Wray made an unannounced trip to Israel Wednesday where he met with officials to discuss the “threat landscape" facing the U.S. and Israel, the FBI said.

"Director Wray’s key focus is the work the FBI continues to do to confront the elevated threat as foreign terrorist organizations have expressed support and praise for the attacks on Israel and threatened to attack U.S. interests both abroad and in the homeland," the FBI said in a statement. "The FBI has and will continue to be responsive to requests from the Government of Israel to provide support in their ongoing efforts to keep their citizens safe from the threats and acts of terrorism."

The delegation that Israel sent to Egypt to take part in negotiations on Tuesday over a potential cease-fire or hostage deal with Hamas will not return for more talks this week, an Israeli political source told ABC News on Wednesday.

Officials from Egypt, Qatar and the United States have been mediating talks between Israel and Hamas since war broke out on Oct. 7.

Israeli Prime Minister Benjamin Netanyahu said Wednesday that negotiations "can move forward" when "Hamas drop[s] their delusional demands."

But Israeli labor leader Merav Michaeli is criticizing the prime minister, saying, "Netanyahu's refusal to send a delegation to the follow-up talks on the hostage deal shows, once again, that he really does not see an urgent need to bring the hostages home. We must not allow Netanyahu to abandon our hostages for the benefit of his political survival."

-ABC News' Jordana Miller and Morgan Winsor

A U.S. citizen has died in the West Bank, the State Department confirmed on Tuesday -- marking what is potentially the second killing of an American in the occupied territory in recent weeks.

State Department Spokesperson Matthew Miller said during a press briefing on Tuesday that the administration was "still in the gathering information stage." He did not provide additional details, including identifying information for the deceased or the apparent cause of death.

The death comes after a 17-year-old Palestinian-American was fatally shot in the West Bank on Jan. 19. Israeli police said at the time that its internal affairs department was investigating a firearm discharge involving an off-duty law enforcement officer, a soldier and a civilian.

-ABC News' Shannon K. Crawford