Israeli military leaders see danger in the lack of a plan for governing Gaza after the war.

With Israeli troops returning to clear Hamas for the second or third time from parts of northern Gaza, and fighting farther south in Rafah, too, Israel’s government has found itself confronting more vocal discontent from an important constituency: its own military leaders.

Current and former senior military officers have begun to argue more openly that because the government has failed to roll out a plan for what follows the fighting in Gaza, Israeli troops are being forced — in the eighth month of the war — to battle again for areas of the territory where Hamas fighters have reappeared.

Two Israeli officials, who spoke on the condition of anonymity to avoid professional repercussions, said some generals and members of the war cabinet were especially frustrated with Prime Minister Benjamin Netanyahu for failing to develop and announce a process for building an alternative to Hamas to govern Gaza.

There was little expectation, among officials or experts, that a new government would be formed while combat raged. But “clear, hold and build” is the widely accepted practice for fighting an insurgency. And to a growing number of critics, Israel appears to be simply stuck in clearing mode, increasing the risks for Israeli soldiers and Gazan civilians while cease-fire talks remain stalemated.

The two officials said Mr. Netanyahu’s unwillingness to have a serious conversation about the latter phases of the Gaza campaign — the “day after” the fight — has made it easier for Hamas to reconstitute itself in places such as Jabaliya in northern Gaza.

Israel first attacked Hamas’s ranks there in October — and returned this week with another air and ground assault.

Much of the global criticism of Israel over the war has focused on the ever-rising civilian death toll. But Eran Lerman, Israel’s deputy national security adviser from 2006 to 2015, said it also stemmed in part from “the lack of coherent vision for the day after.”

Israel’s generals should have asked tougher questions months ago, according to some analysts.

“Hamas or some organization like it is going to survive — unless you’d have started much earlier to align the sun, the moon and the stars into something that would create a counter,” said Aaron David Miller, a senior fellow at the Carnegie Endowment for International Peace. “There is no counter. That’s the problem.”

Prime Minister Benjamin Netanyahu has resisted calls to bring the fighting to an end, arguing that there can be no civilian government in Gaza until Hamas is destroyed. On Monday, in a podcast interview, he said the territory needed “sustained demilitarization by Israel” first, because “no one’s going to come in until they know that you either destroyed Hamas, or you’re about to destroy Hamas.”

But with a growing number of analysts and officials questioning whether Israel can accomplish such a broad goal, the more vocal critique from parts of the military reflects a gradually widening rift with the Netanyahu government.

Military officials, along with the White House and other countries, have grumbled privately for months about a lack of postwar strategy, but the volume of discord is now rising internally and externally as the scale of the counterinsurgency campaign becomes more visible.

While Israeli strategists have always said they expected troops to go back to some areas of Gaza in later phases of the war to stamp out pockets of resistance, there is a growing sense of it being more difficult now than it needed to be.

The two Israeli officials said that without an alternative to Hamas for administering the basic needs of the people, or to offer hope for a return to normal life, it is easier for Hamas to slip back into its old haunts or create new ones, making the fight harder for Israeli troops.

The military’s leaders “are frustrated that they have been given a military assignment that ends up repeating like Groundhog Day, because the larger strategic and political questions haven’t been answered by the government,” said Michael Koplow, an analyst at Israel Policy Forum. “If the military frustrations and the angst of military families becomes louder, it will compound the government’s problems and put even more strain on the coalition.”

For Mr. Netanyahu, the political considerations involve trying to hold together a government with right-wing parties that have demanded an all-out assault on Gaza over American objections, and are unwilling to support what Arab countries have demanded as a prerequisite for their help in Gaza: a path to a Palestinian state.

If Mr. Netanyahu veers too far from the demands of his coalition partners, they have threatened to topple the government, which could leave Mr. Netanyahu to face a series of corruption allegations without the powers he has as prime minister.

Dr. Lerman, the former deputy national security adviser, recently published a proposed plan with other scholars at the Wilson Center that calls for a multinational authority to administer and police Gaza, led by the United States, Egypt and other nations. It has been shared with Israeli authorities.

Other proposals have included efforts to strengthen the Palestinian Authority that now governs part of the Israeli-occupied West Bank, but the Israeli government has also rejected that idea, arguing that the authority is not a competent, credible partner.

American officials over the weekend and on Monday repeated their argument that without a diplomatic solution, Israel would face what the United States confronted in Iraq and Afghanistan: a bloody war of attrition that drags on for years.

“They will be left holding the bag on an enduring insurgency because a lot of armed Hamas will be left, no matter what they do in Rafah, or if they leave and get out of Gaza, as we believe they need to do,” Secretary of State Antony J. Blinken said over the weekend. “Then you’re going to have a vacuum, and a vacuum that’s likely to be filled by chaos, by anarchy, and ultimately by Hamas again.”

Former Israeli officials sounded warnings about a lack of postwar planning even before the ground assault in Gaza began. On Oct. 14, a week after the devastating Hamas-led attack that killed about 1,200 people, Israeli officials say, and touched off the Israeli military offensive, Tzipi Livni, a former foreign minister, called on the government to consider Gaza’s postwar future.

“Otherwise,” she said then, “we would get stuck there unnecessarily and with a heavy price tag.”

In an interview Tuesday, she said this was exactly what had happened.

“Just imagine if we had decided this before, and started working earlier with the U.S., the Palestinian Authority, Egypt, the U.A.E. and the Saudis,” she said, referring to the United Arab Emirates. “It would be much easier.”

Johnatan Reiss and Gabby Sobelman contributed reporting.