ANALYSIS: Is Israel winning the war against Hamas?

TEL AVIV -- In the aftermath of Oct. 7, when the Hamas terrorist group stormed the Gaza border and rampaged through southern Israel, the Israeli public was united by grief. Israeli Prime Minister Benjamin Netanyahu, a polarizing figure in Israeli politics, declared war with a united military and government.

Netanyahu has continued to maintain the war will go on for as long as necessary and has repeatedly vowed to destroy Hamas.

Behind the scenes, Israel's war aims with regard to eradicating Hamas appear to have gradually softened. Rather than destroying Hamas in its entirety, Defense Secretary Yoav Gallant has instead envisaged a path to victory that would see a demilitarization of the Gaza Strip and the removal of Hamas as the governing body in Gaza.

After almost four months of war and no end in sight, there are now growing questions about whether Israel will be able to accomplish its stated goals in Gaza.

Is it possible to defeat Hamas?

In Israel, at least 1,200 people have been killed and 6,900 others injured since Oct. 7, according to the Israeli prime minister's office. Since then, more than 26,000 people have been killed in Gaza and over 65,000 others injured, according to the Hamas-run Gaza Health Ministry. Israeli officials say 556 Israel Defense Forces soldiers have been killed, including 221 since the ground operations in Gaza began.

In recent briefings to the media, Israeli officials have said about a quarter of Hamas fighters in Gaza have been eliminated. It's believed there are an estimated 30,000 Hamas fighters. According to intelligence assessments reportedly seen by the Wall Street Journal, around 80% of Hamas's tunnel network is still intact. For some observers, those numbers fall short of what would be expected, given the widespread destruction brought by Israel's bombing campaign so far in the Gaza Strip. Hamas has previously claimed to have built 500 kilometers -- more than 300 miles -- of tunnels under Gaza.

Retired Maj Gen. Giora Eiland, who served in the Yom Kippur and First Lebanon wars and headed the Israeli National Security Council from 2004 to 2006, told ABC News the IDF was achieving significant tactical military victories against Hamas, but so far has not come close to inflicting a strategic defeat on the terrorist group.

"From the military point of view, the operations in Gaza are quite successful. We managed to destroy many of the military, munition and weapons facilities. We managed to neutralize many of the tunnels," he said. "But it takes much longer than expected. I would even say [Hamas] does not really feel the real pressure."

Eiland said he strongly supports continuing the war but said that without a return to a full blockade of humanitarian aid and supplies to Gaza, the defeat of Hamas might not be achievable or could take as long as a year -- time he said he doubts Israel has.

The reimposition of such a blockade is almost certainly unacceptable to the United States and Israel's other allies, particularly after Israel was forced to defend itself against an allegation of genocide by South Africa in the International Court of Justice.

Daniel Levy, president of the U.S./Middle East Project, a nonprofit policy institute focusing on U.S. foreign policy in the Middle East, said Israel's intensive campaign against Hamas was now showing its limits, with Hamas still intact.

"What we're seeing is the law of diminishing returns kick in," he told ABC News. "There's been some killing of Hamas fighters. There's been a clear reduction in the Hamas rocket capacity. But Hamas is very much present."

Many observers from the beginning of the war have questioned the feasibility of destroying Hamas given its nature as a movement within Palestinian society, and Israel's operation itself would potentially fuel more support for it, according to Levy.

"Hamas is a resistance movement. It's an idea," Levy said. "So the idea that that can be defeated was never a realistic Israeli reading of the reality it lives it."

The hostages

Concerns have also grown in Israel itself over whether the goal of destroying Hamas may be in conflict with rescuing the remaining hostages held in Gaza.

About 136 hostages remain captive by Hamas, according to the Israeli prime minister's office and the IDF. At least 33 of those hostages are believed to be dead in Hamas captivity, with their bodies still held in Gaza, the Israeli prime minister's office and IDF say. There was a temporary cease-fire at the end of November during which Hamas freed over 100 of the more than 200 people its militants took hostage during the Oct. 7 surprise attack on Israel. In exchange, Israel released more than 200 Palestinians from Israeli prisons.

In the most high-profile dispute within the war cabinet so far, retired Gen. Gadi Eisenkot, whose son was killed fighting in Gaza, openly criticized Netanyahu's leadership in comments this month to Israel's Channel 12 News, saying the highest chance of securing the hostages' release would be to agree to a cease-fire, and that the likelihood of a military rescue was "extremely low."

Since Hamas took more than 230 hostages into Gaza on Oct. 7, only one -- Pvt. Ori Megidish -- was rescued by the Israeli military.

"There is today a growing tension between the two, let's say, goals of the war. On the one hand, to crush Hamas, and on the other hand, to release the hostages," Eiland said. "Hamas understood this very well."

Negotiations to release the remaining hostages continue, but Hamas' insistence they be released in exchange for a permanent cease-fire, and Israel's full withdrawal from Gaza, would represent a defeat for Israel, Eiland said.

"If Israel agrees to this formula, then maybe we will get the hostages back. But [it means] we have lost the war," he said.

Isolation and a wider war

Israel has found itself isolated on the international stage, according to Levy, after launching a major offensive in Gaza he said has "played into Hamas' hands."

"Not only in terms of failures to succeed on the ground, but also the narrative," he said. "The mass mobilization around Palestine, Palestine becoming almost an avatar for injustice in the global order, the global South siding in, as it's done, South Africa, South Africa taking Israel to the International Court of Justice. Israel has lost this war, and it's a question now of cutting its losses, because I fear that from an Israeli perspective, this only gets worse."

The United Nations has warned that disease and hunger are spreading across the Gaza Strip, with the U.N. Relief and Works Agency for Palestine Refugees (UNRWA) saying earlier this month that 570,000 Gazans are currently facing "catastrophic hunger." International organizations have also said hospitals in Gaza are experiencing "catastrophic" situations and operating far beyond capacity.

The IDF has said it is only targeting Hamas and other militants in Gaza and alleges that Hamas deliberately shelters behind civilians, which the group denies.

A dossier from the Israeli military recently revealed new allegations against employees of the UNRWA who are accused of being involved in the Oct. 7 Hamas attack on Israel. The report obtained by ABC News alleges that 13 UNRWA employees participated in the Oct. 7 attack, including six employees who allegedly infiltrated Israel.

Meanwhile, the specter of a wider, regional war, involving the likes of Hezbollah and Iran, has haunted the conflict.

U.S. diplomatic efforts in the region have focused on preventing escalation, but some in Israel have advocated for deeper strikes into Lebanon.

Since Oct. 7, tensions have simmered in the north with militant group Hezbollah, with both sides trading fire and tens of thousands of people forced to leave their homes on either side of the Lebanese border.

Senior Israeli officials have repeatedly warned the situation is unacceptable and that Israel could be forced to take military action to push Hezbollah forces back unless a diplomatic solution can be found. The Biden administration has dispatched an envoy to try and seek such a solution, but many in Israel remain skeptical it can succeed. For the likes of former Israeli Ambassador to the U.S. Michael Oren, the perilous situation in the north means they feel containment efforts are unlikely to succeed.

Oren said he advocates for a preemptive strike on Hezbollah, which possesses a far stronger and more advanced force than Hamas. He argued Israel must be given the time to continue the war and complete Hamas' destruction -- even if Israel has to go it alone, without the United States' support.

"To paraphrase John Lennon in a way that John Lennon wouldn't like, you have to give war a chance here, because if you don't give war a chance, you will not have any peace," Oren said. "There'll be no peace as long as Hamas is a force in this region, and there'll be no peace between Israel and Arab states if we aren't shown to be strong."

Asked whether that meant the war would go on for many months, with thousands more civilian casualties, he said: "We have no choice."