Israel says an assault on Gaza’s southernmost city is vital to dismantling Hamas and has proposed evacuating civilians. But more than a million people have taken refuge in the city.

After weeks of delays, negotiations and distractions, Israel appeared to hint this week that its assault of Rafah — a city teeming with displaced persons above ground and riddled with Hamas tunnels below — was all but inevitable.

In what some analysts and residents of the city saw as a sign of preparations for an invasion, an Israeli military official on Tuesday gave some details that include relocating civilians to a safe zone a few miles away along the Mediterranean coast. Just a day earlier, Israeli warplanes bombed Rafah, increasing fears among some of the civilians sheltering there that a ground assault would soon follow.

Such indicators that Israel may be preparing an invasion, said Marwan Shaath, a 57-year-old resident of Rafah, “are terrifying and mean they may really be close to starting an operation.” Mr. Shaath, who lives in Gaza but is employed by Hamas’s Palestinian rivals in the occupied West Bank, added, “Our bags have been packed for months now for the time of the evacuation.”

Israel insists that a push into Rafah is necessary for achieving its goals of eliminating the militants sheltering in a network of tunnels beneath the city, capturing or killing Hamas leaders presumed to be there and ensuring the release of the remaining hostages captured during the Hamas-led Oct. 7 attacks on Israel.

But more than one million Gazans, many of them previously displaced from other parts of the territory by Israeli bombardment, are sheltering in the city in makeshift tents. In the case of an invasion, one Israeli military official said, civilians would probably be moved to Mawasi, a designated humanitarian zone. But the zone is already overflowing with displaced people, who warn that it lacks the infrastructure, including clean water and latrines, to handle such an enormous influx.

“Where do these million people go?” asked Ali Jarbawi, a former Palestinian Authority official who teaches at Birzeit University in the occupied West Bank. “We haven’t seen signs of the Israelis’ evacuating people.”

Mr. Shaath, the Rafah resident, said that despite being prepared to go he was in no rush. “At the end of the day, Mawasi is 25 minutes walking from where I live,” he said, adding that he would not evacuate “until the operation really begins and my residential block is labeled a fighting area.”

Exactly when such an operation might start remains an open and critical question.

Hamas, analysts said, is bottled up in southern Gaza, heavy fighting has mostly subsided, a cease-fire remains a possibility and delaying helps placate the Americans, who have called for a detailed plan to protect civilians ahead of an invasion.

Some analysts have even suggested Israel may never invade Rafah and that the threat alone is a means to leverage Hamas amid cease-fire and hostage negotiations. When pressed, Prime Minister Benjamin Netanyahu of Israel said this month that a date had been set for the invasion, but he provided no other details. Yoav Gallant, the Israeli defense minister, reportedly denied such a plan to his American counterpart, Lloyd J. Austin III.

Beyond just moving against Rafah, any strategy for southern Gaza must also include broader plans, analysts said: both for securing the narrow ribbon of land along the Egyptian border, through which weapons have been smuggled; and the even thornier question of who will govern the enclave when the fighting is over.

Most officials and analysts said an assault on the city was not a matter of if, but of when.

The Israelis have to finish off “Rafah in order to realize the first and most important objective of the war,” said Kobi Michael of the Institute for National Security Studies and the Misgav Institute for National Security and Zionist Strategy, both think tanks in Israel. That includes plans “to dismantle the main centers of gravity, civilian and military, of Hamas, to prevent it from re-establishing itself as a military and political authority,” he said.

For his part, President Biden has not strayed from his support of Israel in pursuing that primary goal — dismantling Hamas as a military and political power in Gaza — or of Israel’s other main objective, securing the release of about 100 hostages still believed to be in the territory. But the president has become increasingly vocal in his calls for Israel to reduce civilian casualties and to allow more humanitarian aid into Gaza.

“We cannot support a major military operation in Rafah,” Secretary of State Antony J. Blinken told reporters last week while in Italy. Protecting civilians during such an operation, he added, would be “a monumental task for which we have yet to see a plan.”

To that end, Israel’s proposed expansion of Mawasi for use as a humanitarian zone could be viewed as an effort to placate the United States and other countries regarding civilian deaths in Rafah.

On Tuesday, Volker Turk, the United Nations’ human rights chief, said world “leaders stand united on the imperative of protecting the civilian population trapped in Rafah.”

Chuck Freilich, a former deputy national security adviser in Israel and a critic of the government, said, “An operation in Rafah is necessary to complete the destruction of Hamas’s major military capabilities and is probably inevitable.”

But, he added, there is no urgency to attack now and it could behoove the Israelis to be seen as heeding Washington’s advice and waiting. Egypt, too, is urging caution, fearing that major strikes would send Palestinians fleeing over its border.

Even more important strategically than Rafah, Mr. Michael said, is the roughly 8.7-mile strip of largely unpopulated land along the border with Egypt, known as the Philadelphi Corridor. Israelis believe that much of the extraordinary arsenal and the building supplies Hamas accumulated in Gaza came through Egypt, mostly through smuggling tunnels, Mr. Michael said, as did Yossi Kuperwasser, a reserve brigadier general and former Israeli intelligence officer.

“We must shut down all the infrastructure of the tunnels underneath Rafah used to smuggle money, weapons and people into Gaza,” Mr. Michael said. “If we end the war without blocking the tunnels, we would enable Hamas or any other terrorist organization in the strip to rebuild their military capacities.”

In a recent report, the Institute for National Security Studies in Tel Aviv called on Israel to make “brave decisions” and to develop “a plan for the hermetic closure of the Philadelphi Corridor, in close cooperation with Egypt and the United States.”

“The main goal,” the report found, is not the conquest of Rafah but “to prevent arms and weapons smuggling.”

The current protocol between Israel and Egypt, agreed on when Israel withdrew its troops and settlers from Gaza in 2005, assigns Egypt to secure the border with a force of 750 soldiers equipped to combat terrorism and smuggling. Israeli officials say that the accord is outdated, not least because Hamas took control of the enclave in 2007, and Mr. Netanyahu has vowed to restore security along the border. Egypt says that it has taken significant action to secure the area and eliminate the tunnels, and that some smuggling into Gaza occurs from Israel as well.

“There are now three barriers between Sinai and the Palestinian Rafah, with which any smuggling operation is impossible, neither above nor below the ground,” Egypt’s chief spokesman, Diaa Rashwan, said on Tuesday.

Nevertheless, the United States is brokering an agreement between Egypt and Israel to build a more technologically advanced barrier on the Egyptian side of the border, which would be financed by Washington and could be monitored from afar by the United States and Israel.

Should Israel take Rafah and secure the border, the question of who will govern Gaza after the fighting ends remains unanswered. “The key to rendering Gaza safe for Israelis, and for that matter for Gazans, lies in what follows the fighting,” said Lawrence Freedman, emeritus professor of war studies at King’s College, London.

“From the start the lack of a credible political dimension to Israel’s strategy has been its most evident flaw,” Mr. Freedman wrote in an email. Israel, he added, has failed to appreciate the impact of heavy civilian casualties on its reputation and has also failed to produce a plan for Gaza’s government and its reconstruction, “essential if Hamas is not to return to its former position.”