Israeli forces push deeper into Lebanon in widening war campaign

On Thursday, Israel’s military for the second day in row said its troops were reaching new targets in southern Lebanon. A day earlier, the military announced six soldiers were killed fighting there, in one of the deadliest single incidents for Israeli troops since the start of the ground operation more than a month ago.

The soldiers were killed in a firefight with at least four Hezbollah fighters who ambushed Israeli troops inside a building, according to an initial Israeli probe. That is a sign of the continual threat Hezbollah’s guerrilla warfare presents to Israeli soldiers going deeper into Lebanon.

The expanding operation comes as senior Israeli and American officials in recent days have expressed optimism over U.S. efforts to broker a cease-fire between Israel and Hezbollah, saying a deal is reachable before President-elect Donald Trump takes office, though key sticking points remain.

At the start of the land campaign, Israel said its ground forces were entering Lebanon with the goal of removing Hezbollah’s presence along its border and destroying years of preparations by the Iranian-backed militant group to invade northern Israel.

Since the start of October, Israeli troops have killed hundreds of Hezbollah operatives. They have also been razing villages along Lebanon’s border, destroying underground fortifications and seizing weapons, including advanced antitank missiles, according to the Israeli military.

“We have expanded the ground maneuver in southern Lebanon and are operating against Hezbollah targets in the Dahiyeh quarter of Beirut and wherever necessary," Israel’s new defense minister, Israel Katz, said earlier this week, referring to a Hezbollah stronghold.

Israeli military spokesman Lt. Col. Nadav Shoshani declined to say where and how much deeper Israeli troops have advanced into Lebanon. “We’re going according to villages that pose an immediate threat on Israeli communities operating near the vicinity of the border," he said Thursday.

Some security experts view Israel’s expanding ground operation as a tactical step to neutralize the threat of Hezbollah antitank missile attacks on Israeli border towns. They say the move is needed to convince around 60,000 civilians that they can safely return to areas they fled in fear of a Hezbollah invasion at the start of the war in October 2023. Hezbollah is now launching more than a hundred rocket attacks a day toward Israel, and its drones have penetrated air defenses to strike sensitive sites.

Others say a deeper push into Lebanon is a risky gambit to press Hezbollah to agree to a cease-fire on Israel’s terms. If Hezbollah doesn’t relent, they argue, Israel could be drawn into a protracted conflict deep inside Lebanon.

“It can spiral out of control," said Tamir Hayman, a former head of Israeli military intelligence and executive director of the Institute for National Security Studies in Tel Aviv.

Hayman argued that Israel was losing the window of opportunity where its recent achievements against Hezbollah, including killing nearly all its leadership, could be leveraged into the best possible cease-fire terms. If Israel waits too long, Hezbollah, with Iran’s help, could reconstitute itself, refuse a cease-fire and bog Israel down with guerrilla warfare, he said.

The broad outlines of the U.S.-brokered proposal would see Hezbollah moving all of its forces and weapons north of the Litani River—a waterway roughly 18 miles north of the Israeli border and within 8 miles of the boundary at its closest points. The Lebanese military and United Nations peacekeepers would be charged with preventing the militant group from returning.

Israel’s strategic affairs minister, Ron Dermer, on Sunday gave Trump a briefing on the proposal at his Mar-a-Lago club in Florida. Trump, according to the Israeli officials, signed off on the plan and expressed hope that it would get done before he entered the Oval Office on Jan. 20.

Spokespeople for the White House and Trump’s transition team didn’t respond to requests for comment. But Amos Hochstein, the lead U.S. negotiator on the talks, told reporters this week “there is a shot" at striking a cease-fire agreement soon. On Thursday, the U.S. ambassador to Lebanon delivered a draft of the cease-fire proposal to Lebanon’s parliamentary speaker, Nabih Berri, who is close to Hezbollah, according to people familiar with the matter.

Israeli officials say the main sticking point is ensuring Israel will be able to enforce the cease-fire agreement if the U.N. and Lebanese armed forces fail to do so. Israel is also seeking ways to prevent Hezbollah from replenishing weapons inventories degraded by Israel. This includes getting the help of Russian authorities present in Syria to prevent arms smuggling from there into Lebanon.

“There is some progress in the attempts to reach a settlement in Lebanon," said Israel’s new foreign minister, Gideon Sa’ar, on Monday. “Our main challenge will be to enforce what is agreed upon."

Despite Israeli and American optimism, the Lebanese government and Hezbollah recently rejected Israel’s demand to enforce any cease-fire itself, according to a person familiar with the negotiations.

Instead, they proposed that, in addition to the Lebanese military, Israeli military and the U.N., a fourth guarantor be added to the committee responsible for enforcing the cease-fire agreement, which would likely be the U.S., the person said.

Polling released Wednesday by the Institute for National Security Studies found 80% of the Israeli public believes that the current security situation isn’t safe enough to allow most residents to return to northern communities.

Alongside its expansion of the ground operation, Israel in recent days has also increased airstrikes in southern Lebanon and in Hezbollah’s Beirut stronghold, Dahiyeh. The strikes in Beirut have increased in frequency in the past week, hitting residential districts there at least every other day for more than a week.

Israel’s military says it has been hitting stockpiles of Hezbollah weapons, including ballistic missiles, land-to-sea missiles and rocket launchers.

“At the moment the thinking is, let’s enhance the pressure and destroy as many terrorists and infrastructure and give the understanding that every day Hezbollah and Lebanon don’t agree to a kind of solution, they will be degraded more and more," said Amir Avivi, a former senior military official who heads a security-oriented think tank in Israel.

He said that Israel would need to be cautious about being drawn too far into Lebanon and that a depth of around 6 miles would be sufficient to protect Israelis from Hezbollah’s antitank missile fire.

But rather than just protect its border, Avivi said Israel should revise its goal to completely destroy Hezbollah as a military organization. This, he said, would require Israel to launch more attacks against Iran, or else Tehran would soon rebuild its Lebanese proxy group.

Katz, Israel’s defense minister, this week said Israel would keep fighting until it achieves its war aims in Lebanon, which he said included disarming Hezbollah. This was the first time disarming Hezbollah was stated as an Israeli war aim.

Israel Ziv, a retired Israeli general and veteran of multiple wars, said that the expanded ground campaign, besides providing leverage in cease-fire talks, could help Israel secure a perimeter in southern Lebanon to prevent Hezbollah from coming closer to the border. Still, he said Israel would need to be cautious not to get ensnared too deep into Lebanon.

“If in the beginning it’s about pressure, later on it’s about being stuck in the swamp. It’s a risk," he said.

Adam Chamseddine, Stephen Kalin and Alex Ward contributed to this article.

Write to Dov Lieber at dov.lieber@wsj.com