Israel, Hezbollah fighting stretches a cease-fire deal to the limit

Israel still has troops on the ground in Lebanon and has continued to regularly strike Hezbollah infrastructure and weapons depots. In a complaint to the United Nations Security Council, Lebanon accused Israel of some 800 land and air attacks since the cease-fire came into effect on Nov. 27.

Israel has repeatedly accused Hezbollah, a U.S.-designated terrorist group that controls much of southern Lebanon, of maintaining fighters and weapons including rockets in the south that threaten its security, also in violation of the two-month truce.

The trouble comes ahead of a Jan. 26 deadline for Israeli forces to leave, following their incursions into southern Lebanon across almost the entire swath of the border. Under the terms of the truce, the U.S.-backed Lebanese military is to move in as Israel leaves and work with U.N. peacekeepers to keep the area clear of the Hezbollah militia, a U.S.-designated terrorist organization.

But Israel is worried that the undermanned, outgunned Lebanese military isn’t up to the task of preventing Hezbollah from eventually rebuilding near the border areas. Defense Minister Israel Katz said over the weekend that if Lebanon’s army doesn’t enforce the agreement, Israel will step up military action.

“If this condition isn’t met, there won’t be a deal," Katz said.

A collapse of the deal would risk reigniting the fighting that has depopulated a stretch of northern Israel and, according to Lebanon’s health authorities, left thousands of Lebanese dead. It could also undermine a policy achievement for Biden administration officials who have worked all year to prevent the war that began in the Gaza Strip from spreading across the region.

U.S. officials arrived in Beirut on Monday to discuss progress on the deal and said Israeli troops would pull out of the country in phases moving from west to east. They said Israel began to withdraw from the Mediterranean seaside town of Naqoura on Monday and would continue to turn over territory to the Lebanese army.

Israel also withdrew from cities and towns including Tyre and al-Khiyam, though its forces remain in many other areas.

U.S. officials said the Lebanese army was up to the job of securing the south. The U.S. and France plan to support the Lebanese army with training and funds.

“Implementing the cease-fire agreement in southern Lebanon is not smooth, but it is successful," U.S. Special Envoy Amos Hochstein said after co-chairing a meeting of the international committee overseeing the cease-fire. “I think today’s withdrawal of the Israeli military back into Israel on the western side will be followed by other withdrawals until they are out of Lebanon completely."

The Biden administration assesses that Israeli forces are on track to leave southern Lebanon by the Jan. 26 deadline. More than a third of the Israeli forces in Lebanon have left, a person familiar with the matter said.

Lebanese Prime Minister Najib Mikati, speaking after a cabinet meeting, said the country is committed to carrying out its responsibilities under the deal and accused Israel of inventing situations that threaten the truce.

The Israel-Lebanon truce aimed to end fighting that began shortly after the Hamas-led attacks on southern Israel on Oct. 7, 2023, which, according to Israeli officials, left some 1,200 dead and around 250 taken hostage. Hezbollah began firing rockets at Israel to support Gaza, setting off a back and forth exchange that ran for months.

Hezbollah stood down after it was battered by intense bombing, ground maneuvers and intelligence operations launched by Israel last fall. It has made veiled warnings that it could again take military action if Israel doesn’t meet the deadline for withdrawing.

“Our patience may run out before 60 days or persist longer," Hezbollah chief Naim Qassem said in a speech on Jan. 4. “When we decide to act, you will see it directly."

Some Israeli analysts say the agreement was flawed from the outset—difficult to enforce, with too tight a time frame and a reliance on the Lebanese armed forces, which failed to enforce the terms of a cease-fire deal that ended hostilities between Israel and Hezbollah in 2006.

“This agreement is a very, very problematic agreement," said Vice Admiral Eliezer Marum, a former chief of the Israeli navy and the former government director for rehabilitating Israel’s north during the current war.

The job of targeting remaining Hezbollah infrastructure and confiscating weapons is easier to do with troops inside Lebanon, and Israel could use more time, Israeli security officials and analysts say.

“Israel optimally would want a few months to work," said Orna Mizrahi, a former Israeli deputy national security adviser.

Despite Israel’s problems with the deal, the agreement has succeeded in stopping the heavy fighting that went on for months. Analysts say both sides have little interest now in escalating. Hezbollah has largely withdrawn its heavy infrastructure from southern Lebanon, if not many of its personnel, and is severely weakened. Israel killed much of its senior leadership, including former chief Hassan Nasrallah, and has weakened its main sponsor, Iran.

Israeli reservists, meanwhile, are fatigued after fighting for 15 months on several fronts. Israel also is trying to convince tens of thousands of evacuated residents that they can safely return to their homes near the border with Lebanon.

Both countries also have their eyes set on an additional deadline—Jan. 20—when President-elect Donald Trump takes office in Washington. Trump hasn’t said much about the truce beyond that he wants fighting to end in the Middle East.

Michel Fayad, a former adviser to Lebanon’s minister of economy and trade, said Hezbollah is viewed as the war’s loser in Lebanon, and it is now looking for leverage as Trump takes over. “The tensions are very high," Fayad said.

Adam Chamseddine, Saleh al-Batati and Alexander Ward contributed to this article.

Write to Anat Peled at anat.peled@wsj.com