The world on Sunday got its first look at how devastating an Israeli invasion of Rafah — Gaza’s southernmost city, where more than a million Palestinians have sought safety amid Israel’s military operations — might be.

At least 67 people were killed by Israeli airstrikes, and the death toll is expected to increase, according to the Gaza health ministry. The strikes coincided with a raid by the Israel Defense Forces that recovered two Israeli hostages. The hostages were the first freed since November; an estimated 132 of the original 250 taken by Hamas and its allies during their October 7 attack on Israel remain captive or are presumed dead.

The strikes come amid reports that Israel is considering a ground invasion of Rafah, which Israel claims is the last remaining Hamas stronghold. Such an operation would require massive evacuations; the city’s population is roughly five times larger than it was before the war, swollen by refugees fleeing the fighting in northern Gaza. Those residing in Rafah can’t go any further south as the city abuts Gaza’s border with Egypt, which is largely closed.

They also arrive as ceasefire negotiations between Israel and Hamas have stalled and as protests calling on the Israeli government to be more flexible in its approach to freeing remaining hostages have intensified. Despite these pressures, Prime Minister Benjamin Netanyahu vowed to continue Israel’s fight until it had achieved a “total victory” that involves Hamas’s complete destruction.

Increasingly, that total victory seems unlikely. Hamas has so far withstood Israel’s attacks; it’s unclear that a more aggressive operation in Rafah would change that. Ground battles in the densely populated area could create high civilian casualties, something that could strengthen the genocide case against Israel at the Hague. It would also likely lead to those critical of the war putting renewed pressure on Israel’s allies, particularly the US, to intervene.

US officials are watching Israel closely and have become more privately critical of its tactics in Gaza. Biden called Israel’s war “over the top” in public remarks last week, and according to an NBC report has privately denigrated the country’s strategy and leaders in explicit terms. This rhetoric seems markedly stronger than it was before, and that might be designed to distance the US from what Israel is planning in Rafah and head off what would be the disastrous humanitarian consequences of a ground invasion. But the administration is still outwardly continuing to push for military and diplomatic support for Israel.

If Israel intends to invade Rafah, “the only thing that can really stop them is a big US push that might require the US to be more coercive and use more of the tools that it has in terms of leverage, whether that’s diplomatic support or military aid,” said Michael Hanna, US program director at the International Crisis Group. That doesn’t appear likely to happen. But, Hanna said, “I think it’s the kind of juncture in which those things should be deployed because of how serious the consequences might be.”

Why would a ground invasion of Rafah be so devastating?

A ground invasion of Rafah would be calamitous because of how crowded the city is and because of its location.

Most of the 1.7 million displaced Palestinians are currently sheltering in Rafah, fleeing there after the IDF instructed them to evacuate their homes months ago. The Rafah border crossing with Egypt is the only way in and out of Gaza right now, but there are strict limits around who and what are allowed in and out. That said, the crossing has provided a critical artery for humanitarian aid and some Palestinians who were able to secure authorization to leave.

All of that means a ground invasion of Rafah and continued bombing in the densely populated area would be bound to cause high civilian casualties. And it would severely hamper the delivery of desperately needed supplies at a time when Palestinians are already thirsty and starving and hospitals have been under siege.

Those living in Rafah would have few places to go in the event of a ground operation; most of Gaza has already been rendered uninhabitable, per the United Nations’ humanitarian chief. And not everyone would be able to leave: There are injured and elderly sheltering in Rafah.

“It would be an absolute humanitarian disaster if there were to be more escalation in Rafah,” Lisa Macheiner, a Doctors Without Borders project coordinator in Gaza, said in a statement. “There is no space. There are hundreds of thousands of people who have tried to find a safe space and have nowhere to go.”

It could potentially trigger a massive rush of Palestinians toward Egypt. If that happens, Egypt has threatened to abandon the 1978 Camp David Accords, its watershed treaty with Israel that marked a key step toward broader Arab recognition of Israel. That could trigger a serious crisis in the Middle East, where regional conflict is already brewing.

The Biden administration has indicated that the US also would not support an invasion of Rafah and has raised concerns about conducting a military operation during the Muslim holy month of Ramadan, which begins March 10.

Nevertheless, Netanyahu announced on Friday that he had told military leaders to draft a plan to evacuate civilians from the area. “It is impossible to achieve the goal of the war of eliminating Hamas by leaving four Hamas battalions in Rafah,” Netanyahu’s office said in a statement.

As some Israel analysts have suggested, this might just be rhetoric designed to extract more concessions from Hamas in negotiations, and Israel would not want to risk further alienating its biggest strategic partners.

“Benjamin Netanyahu is extremely skillful at sounding tough and acting cautiously. Is that what he’s doing now? I don’t know,” said Jon Alterman, director of the Middle East Program at the Center for Strategic and International Studies.

But not everyone thinks so. “It’s very possible that this is posturing and it is about putting pressure on Hamas to have additional leverage in the talks, which are still ongoing,” Hanna said. “But if the talks do fail, there might be a huge amount of pressure after all of this public bluster to go forward. And I’m just not certain that the Israelis are looking at this as just posture.”

That uncertainty is reflective of the risk that Israel could very well decide to go ahead with the invasion, especially given the ways the Israeli government has normalized tactics that once would have been considered extreme. “Israelis have socialized ideas, like hitting a hospital and forcing 1.7 million Palestinians in the strip to flee their homes, that were seen as sort of impossible when they were first announced. And they have followed through,” Hanna said.

What’s the status of hostage and ceasefire negotiations?

It’s not clear exactly how many of the remaining Israeli hostages are still alive in Gaza. When asked about it Sunday, Netanyahu said it’s “enough to warrant the kind of efforts that we’re doing.”

More than 100 hostages were freed as part of a temporary ceasefire agreement between Israel and Hamas in November. Israel rescued a hostage during a military operation in October, the details of which remain unknown. And in December, the IDF accidentally shot and killed three hostages, who were shirtless and waving a white flag.

Given that the IDF’s operations in Gaza have so far proved largely unsuccessful in recovering hostages, there has been growing pressure on the Netanyahu government to reach a diplomatic solution. Thousands protested in Tel Aviv over the weekend to demand a hostage deal and new elections. Families of hostages and their supporters also interrupted a meeting of the Israeli Knesset last month to press for a deal.

US Secretary of State Antony Blinken traveled to the Middle East last week with the intention of securing some concessions that would lead to diplomatic progress. But he came back empty-handed after Netanyahu rejected what he called a “delusional” proposal that would have allowed all of the hostages to be released in exchange for hundreds of Palestinians in Israeli prisons, as well as an end to the war. Netanyahu also said he won’t accept any deal that leaves Hamas in power in Gaza.

The question is whether he meant what he said, especially given that Blinken has said he still sees room for a deal. But after Sunday’s deadly assault on Rafah, it seems the Netanyahu government may be open to taking a hardline approach.

Ellen Ioanes contributed reporting to this article.