BEIRUT—For nearly two decades, thousands of United Nations peacekeepers have been helpless to stop the Iran-backed militant group Hezbollah from rearming along Israel’s border since the two sides’ previous war.
Now that Israel and Hezbollah have come to a cease-fire ending a year of fighting, the United Nations Interim Force in Lebanon, or Unifil, is again at the center of efforts to keep the peace but still lacks the capability to enforce a buffer zone between the parties, analysts said.
The deal agreed to on Tuesday includes a 60-day implementation period to allow the Israeli military to withdraw and for the Lebanese military to secure the border area and prevent Hezbollah from re-establishing an armed presence there, according to Lebanese officials. An international committee including U.N. peacekeepers would monitor compliance, they said.
But neither the Lebanese military nor U.N. forces could do much to keep Hezbollah from building up fighting positions in southern Lebanon and firing rockets across the border, while Israel responded with military overflights and occasional live fire. The culmination was a year of fighting that began after another Iran-backed militant group, Hamas, attacked Israel on Oct. 7, 2023, from the Gaza Strip. The U.N. peacekeepers have mostly sheltered in their bases after repeatedly coming under fire from both sides.
As a result, Israel insists on the freedom to strike at Hezbollah even after a cease-fire if it believes the U.S.-designated terrorist group poses a threat. An Israeli official said Israel would ensure its own safety.
“We’re not talking about the dissolution of Unifil but also won’t place the future security of northern Israel in Unifil’s hand,” the official said. “We’re not going back to Oct. 6.”
Unifil has had what its defenders say was an impossible mandate since 1978, when Israel invaded Lebanon after a Palestinian militant attack on a bus in central Israel, killing 38 civilians, including 13 children. Unifil’s job was to monitor the Israeli military’s withdrawal from Lebanon and to help the Lebanese government maintain security in the country’s restive south.
But by 1982, Israel was back fighting in Lebanon. After an Israel-Hezbollah war in 2006, Unifil’s job included monitoring Hezbollah’s activities in southern Lebanon and aiding the Lebanese military’s efforts under U.N. Security Council Resolution 1701.
Unifil reports possible violations to the Lebanese army and Israel, which are responsible for correcting the behavior, and to the U.N. secretary-general who relays the findings regularly to the Security Council. Lebanon’s army, however, is underfunded and outgunned by Iran-backed Hezbollah, and there is little in the resolution to force either party into line.
Resolution 1701 was almost immediately violated, and Unifil’s task has grown more difficult over the years. Unifil—which at times conducted some 10,000 patrols a month—increasingly complained that its peacekeepers were prevented from moving around freely and inspecting suspicious locations. It is prevented from entering private property and detaining civilians without permission from Lebanese authorities.
Peacekeepers have complained over the years about an increasingly hostile environment and intimidation by Hezbollah and people in the south, who occasionally accuse them of spying for Israel and attack them. In 2010 Unifil reported that during a 36-hour exercise, its soldiers were attacked by Lebanese civilians who threw stones, assaulted the patrol leader, damaged vehicles and took some Unifil weapons and ammunition.
In 2010, Unifil reported an explosion at a house in a village, but said it was unable to determine the cause, “as possible evidence was tampered with or removed before the UNIFIL investigation team was allowed access to the incident site.” The Lebanese army was only allowed to enter after a standoff with villagers, Unifil said.
Unifil has had some success defusing conflicts and has hosted meetings with the Lebanese army and Israel to keep them from shooting at each other. But over the years, Hezbollah amassed so many arms close to the border that the situation became unsustainable to Israel, said Richard Gowan, U.N. director at the International Crisis Group, a think tank.
“It’s been an open secret for quite a long time that you had Hezbollah operating in quite close proximity to Unifil,” Gowan said.
The peacekeepers’ last report to the U.N. before the Oct. 7 attacks—dated July 2023—highlights the challenges they faced trying to control the situation.
In it, the peacekeepers report a range of concerning incidents including rocket fire, unauthorized weapons, Israeli airspace violations, tunnel construction and a Hezbollah drill with rocket launchers and quadcopters, as well as frequent harassment. A U.N. patrol was stopped in April by masked people and assaulted. The mission complained that it couldn’t get access to suspicious buildings on the border belonging to an environmental group that the U.S. and Israel accuse of being a cover for Hezbollah. Israeli tanks aimed guns at them in several instances, and lasers were pointed at them from both sides.
Unifil says it can report violations, but not unilaterally enforce Resolution 1701.
“We go back to the limitation of the mission’s mandate, what the mission can do and what we cannot do,” Unifil spokesman Andrea Tenenti said. “But it’s up to the Security Council to decide how to move forward. It’s not up to the mission to take further steps that are not within the mission’s mandate.”
Unifil’s observations, however, led to some action. In 2006, Unifil reported “sporadic evidence” of weapons and armed personnel in the border area about once a week, including the discovery of 17 Katyusha rocket launchers and a weapons cache. Unifil said it informed the Lebanese Armed Forces, which confiscated or destroyed the weapons.
It later reported sporadic rocket attacks from south Lebanon into Israel, indicating the presence of weapons in the demilitarized zone. In 2008, it discovered eight rockets ready to be launched at Israel, which the Lebanese army defused and dismantled.
Years later, between December 2018 and April 2019, after being notified by Israel, the peacekeepers confirmed the existence of five tunnels, three of which crossed the Blue Line from southern Lebanon into northern Israel. It provided the coordinates to the Lebanese Armed Forces, and urged them for months to fulfill the country’s commitments under the resolution.
Unifil told Israel that it couldn’t inspect the locations of the tunnels without permission from the Lebanese military because they were on private property, said Jonathan Conricus, a former Israeli military liaison to Unifil and the U.N. When nothing happened after a month, the Israeli military pumped so much cement into one of the tunnels that it spurted out on the other end, flooding a building in a village and gushing into the street, said Conricus, now senior fellow with the Foundation for Defense of Democracies, a Washington-based pro-Israel lobby group.
The Lebanese Armed Forces didn’t reply to a request for comment. It has previously said it has been executing its missions with U.N. peacekeepers to implement the 2006 agreement and defend Lebanon’s national sovereignty, including from Israel. Its defenders say there are various reasons the armed forces haven’t been able to fulfill its mandate, including lack of international funding and the challenges in straddling Lebanon’s sectarian divisions.
In March 2022, Unifil reported more violent incidents and confiscations of its property, including by armed personnel. Later that year, an Irish soldier was killed in an alleged Hezbollah-linked attack while on a peacekeeping patrol. Hezbollah at the time denied involvement.
Unifil has also reported regular Israeli breaches of the 2006 resolution. From 2007 through 2022, the U.N. reported that 22,355 Israeli aircraft violated Lebanese airspace, according to data collected by Earshot, an investigative agency.
Israeli officials say overflights in Lebanon are necessary for intelligence gathering because Unifil hasn’t effectively fulfilled its mandate. They also say that Unifil has failed to accurately report the extent of Hezbollah’s rearmament.
Fouad Siniora, who as Lebanon’s prime minister helped negotiate the 2006 resolution, said it was the responsibility of the parties who agreed to the resolution to uphold it. When they don’t, it puts Unifil in a virtually impossible situation, he said, paraphrasing a line of classical Persian poetry to describe the peacekeepers’ predicament: “You throw a man in the water, then blame him for being wet.”
Dov Lieber contributed to this article.
Write to Sune Engel Rasmussen at sune.rasmussen@wsj.com
