The "special relationship" between the United States and Israel is under pressure amid a looming Israeli ground offensive in Rafah, a city in southern Gaza where it's believed there are about 1.4 million Palestinians taking refuge.
President Joe Biden has called invading Rafah a "red line." Secretary of State Antony Blinken, in a trip to the Middle East last week, said a major military operation there would be a "mistake" that would result in more civilian deaths and worsen an already dire humanitarian crisis.
"There is a better way to deal with the threat, the ongoing threat posed by Hamas," Blinken said during a March 21 press conference in Egypt, though he did not elaborate on what a "better way" would look like.
Vice President Kamala Harris told ABC News in an interview that aired Sunday that the administration was not ruling out consequences if Israeli Prime Minister Benjamin Netanyahu went ahead with an offensive, as he's vowed to do, despite U.S. concerns.
Netanyahu has said going into Rafah is crucial for victory over Hamas and to prevent future terror attacks, and while he appreciates U.S. support, Israel could do it alone. More than 1 million Palestinians have fled to Rafah to seek shelter during the Israel-Hamas war, according to the United Nations. The Israel Defense Forces has said it plans to push civilians toward "humanitarian islands" in the center of the Gaza Strip in advance of an offensive in Rafah.
Tensions boiled over when Netanyahu abruptly canceled an Israeli delegation to Washington on Monday to discuss an alternative approach to Rafah after the U.S. allowed, through abstention, the U.N. to pass a resolution demanding an immediate cease-fire in Gaza for the remainder of Ramadan. The prime minister has since agreed to reschedule the meeting, according to the White House, but no date has been set. The meeting will serve to be an important one, as the U.S. hasn't seen an exact plan for how Israel intends to deal with the civilian population in Rafah -- as the administration has demanded.
Amid the stalemate, questions remain about what more Biden can do to exert pressure on Netanyahu and how the administration could potentially hold Israel accountable for an invasion of Rafah.
"He's limited in terms of what he can do," Guy Ziv, the associate director of American University's Center for Israel Studies, told ABC News. "Any U.S. president is somewhat limited in terms of what they can do, and he's not going to please everyone."
As Aaron David Miller, a former State Department diplomat now at the Carnegie Endowment for International Peace, put it: "Biden's in a box and there's no way out."
Hamas carried out an incursion from Gaza into southern Israel by air, land and sea on Oct. 7, 2023, killing more than 1,200 people and taking 253 others hostage, according to Israeli authorities. More than 32,000 Palestinians have been killed and more than 74,000 others have been injured in Gaza since Oct. 7, amid Israel's ongoing ground operations and aerial bombardment of the strip, according to the Hamas-run Gaza Health Ministry.
The White House has avoided discussing "hypotheticals" when pressed on what consequences or leverage Biden can use when it comes to Israel. National Security Council spokesman John Kirby, when asked that question by a reporter on Monday, sidestepped and reiterated overall U.S. support for Israel and said the U.S. would continue to advocate for minimizing civilian casualties, more humanitarian assistance and a potential hostage deal.
Some Democratic lawmakers, particularly members of the party's progressive wing, have called on conditioning military and financial aid to Israel as the humanitarian situation in Gaza worsens. Humanitarian and international aid organizations have exhaustively warned of the unprecedented crisis unfolding in the strip. The Integrated Food Security Phase Classification (IPC) initiative said earlier this month famine is "imminent" in northern Gaza and may occur between mid-March and the end of May, as the entire population of the strip experiences high levels of food insecurity.
The U.S. has provided Israel with more assistance than any other nation since the Jewish state's inception in 1947. That includes $158 billion (not adjusted for inflation) in military aid and defense funding, according to the Congressional Research Service. Such aid from the U.S. makes up roughly 16% of Israel's total defense budget, the service reported last year.
"It's very, very important," Ziv said of U.S. military aid to Israel. Placing conditions on it, he said, "creates a dangerous precedent for Israel because it just wasn't in the cards up until now."
One of the most notable rifts regarding aid between the two nations came in the early 1990s. Then, under President George H.W. Bush, the United States had agreed to provide Israel $10 billion in loan guarantees to help Soviet Jews resettle in Israel. But Bush didn't issue those guarantees until the Israeli government agreed to curtail settlement activity in occupied territory.
Still, that fissure involved economic aid, not military aid. It also did not come at a time when Israel was engaged in a war with a terrorist organization that threatens its security.
Outrightly conditioning U.S. military aid is not likely, experts who spoke with ABC News agreed, especially as Israel also faces pressure on its northern border with Lebanon.
Biden himself has already ruled out stopping the supply of weapons that would leave Israel unable to defend itself, like those used by its Iron Dome system. In an interview with MSNBC earlier this month, Biden reiterated that while Rafah was a "red line," he would never cut off all weapons to Israel.
"The challenge with explicit conditionality is it creates a contest of wills," Jon Alterman, director of the Middle East program at the Center for Strategic and International Studies, told ABC News.
"Oftentimes, having consequences that are less explicitly laid out and give your partners opportunities to quietly comply are more effective than explicit conditions," he said.
Still, Alterman said he believed if Netanyahu were to ignore the Biden administration's demands about Rafah, there could be other potential consequences, such as slowing down aid or postponing the delivery of offensive weapons. That's been done before, like when President Ronald Reagan delayed military aircraft deliveries to Israel in the 1980s due to an escalating conflict between Israel and Lebanon.
Diplomatic pressures can also continue. Biden has yet to invite Netanyahu to Washington and Senate Majority Leader Chuck Schumer, the highest-ranking Jewish official in the U.S., called for new elections to replace the prime minister, who he described as a roadblock to peace.
The U.S. could continue to abstain or even support United Nations resolutions that Israel finds unfavorable, as it did this week. The U.N. Security Council adopted a resolution demanding a cease-fire in Gaza and the release of hostages, with the U.S. abstaining. Netanyahu asserted the U.N. vote represented a change in the United States' stance on the conflict, which the White House vehemently denied.
"The Rafah operation is part of a broader question of under what circumstances would the Biden administration exercise real leverage and impose any costs or consequences on this Israeli government?" Miller said. "It's almost six months in [to the war] and the administration, despite its frustration and anger with some of the policies of the Netanyahu government, has been reluctant to do so."
The flash point also comes as both Biden and Netanyahu face political pressure at home.
There has been longstanding support in the U.S. for Israel, and while American adults remain broadly supportive of Israelis, opinions had been shifting on Israel and the Palestinians even before the war broke out. A new survey from Pew Research Center published this month found that nearly six months into the conflict, roughly six in 10 Americans (58%) said Israel's reasons for fighting Hamas are valid, but how Israel is carrying out its response to the Oct. 7 attack receives a more mixed evaluation: 38% said Israel's conduct of the war has been acceptable, while 34% say it has been unacceptable.
Biden was the target of protest votes from large Arab American and Muslim communities in swing states such as Michigan and Minnesota over his response to the war. Biden has said he understands the frustration of his critics, and at his State of the Union stressed that the U.S. has been leading efforts to get humanitarian assistance into Gaza, including building a new pier in the Mediterranean so Gaza can receive ships carrying food, water, medicine and more.
In Israel, Netanyahu is facing frustration from many citizens and from members of his own coalition -- some of which began before the war broke out over his proposed judicial overhauls.
"Israel is a country that feels it's facing an existential threat and so the ability of any outside power to shape Israeli actions is limited," Alterman said. "On top of that, you have a political tussle between the prime minister and the president, each of whom is concerned about his political future and feels the other may pose a threat to him."