In an investigation published on Sunday, the New York Times claims that while Hassan Nasrallah, the leader of the Lebanese Hezbollah, was hiding inside a Hezbollah bunker 40 feet underground in the southern suburbs of the Lebanese capital Beirut on September 27, his aides urged him to go to a safer place. But Nasrallah ignored this, according to intelligence collected by Israel and later shared with his Western allies. In his opinion, Israel was not interested in an all-out war.

“What he did not realize was that Israeli spy agencies were tracking his every move — and had been doing so for years,” the newspaper said.

Shortly after, American-made Israeli F-15s dropped thousands of pounds of explosives, destroying the hideout in an explosion that buried Nasrallah and other top Hezbollah leaders. The next day, Nasrallah’s body was found alongside a top Iranian general stationed in Lebanon. Intelligence determined that both men had suffocated to death, according to several people familiar with the matter.

The killing of the charismatic Hezbollah leader, who for decades had led a Lebanese militia in its war against Israel, was the culmination of a two-week offensive. “The campaign combined covert technological wizardry with brutal military force, including remote detonation of explosives hidden in thousands of Hezbollah pagers and walkie-talkies, as well as devastating aerial bombardment aimed at destroying thousands of rockets and missiles capable of hitting Israel,” the paper said.

It was also the result of two decades of systematic intelligence work in preparation for the all-out war that many expected would eventually occur.

The New York Times investigation, based on interviews with more than two dozen current and former Israeli, American and European officials who spoke on the condition of anonymity to discuss covert operations, reveals the extent to which Israeli spies have penetrated Hezbollah. They recruited people to plant listening devices in Hezbollah hideouts, tracked meetings between a top commander and his four mistresses and had near-constant visibility into the movements of Hezbollah leaders.

“It is a story of breakthroughs, as in 2012 when Israel’s Unit 8200 — the country’s equivalent of the National Security Agency — stole a trove of information, including details on secret commanders’ hideouts and the group’s arsenal of rockets and missiles,” the paper says. “There have been stumbles, as in late 2013 when a Hezbollah technician became suspicious of the batteries in the radios. And there have been attempts to salvage their efforts, as in September, when Unit 8200 gathered intelligence that Hezbollah operatives were concerned enough about the radios that they sent some to Iran for inspection.”

Fearing exposure, senior intelligence officials persuaded Israeli Prime Minister Benjamin Netanyahu to order the bombing, setting in motion the campaign that culminated in the assassination of Mr. Nasrallah.

“The Israeli elimination of Hezbollah was a major victory for a country that had suffered the biggest intelligence failure in its history a year earlier, when Hamas-led fighters invaded on October 7, 2023, killing more than 1,200 people and taking 250 hostages,” the paper says.

“Hezbollah’s campaign, part of a broader war that killed thousands of people in Lebanon and displaced more than a million, weakened one of Israel’s greatest adversaries and dealt a blow to Iran’s regional strategy of arming and funding paramilitary groups bent on Israel’s destruction. The weakening of the Iran-led axis reshaped the dynamics in the Middle East, contributing to the fall of the Assad regime in Syria,” she added.

“The contrast between Israel’s approach to Hezbollah and Hamas is stark and devastating. The intense intelligence focus on Hezbollah shows that the country’s leaders believe the Lebanese militant group poses the greatest imminent threat to Israel. Yet it was Hamas in the Gaza Strip, a group that Israeli intelligence believed had neither the desire nor the ability to attack Israel, that launched a surprise attack that caught the nation by surprise.”

Building a network of sources

The 2006 war between Israel and Hezbollah was a bloody stalemate, the paper says. Israel withdrew from Lebanon after 34 days of fighting that began after Hezbollah kidnapped and killed two Israeli soldiers. The war, which failed to achieve Israel’s goals, was a humiliation that led to a commission of inquiry, the resignation of senior generals, and a review of the quality of Israeli intelligence by the security services.

But operations during the war, based on Israeli intelligence gathering, formed the basis for Israel’s subsequent approach. One operation planted tracking devices on Hezbollah’s Fajr rockets, which gave Israel information about munitions hidden inside secret military bases, civilian storage facilities and private homes, according to three former Israeli officials. In the 2006 war, the Israeli air force bombed the sites, destroying the rockets.

In the years following the 2006 war, Nasrallah was confident that his group could win another conflict with Israel, which he likened to a spider’s web—a distant threat that could be easily ignored. As Hezbollah rebuilt, Mossad, Israel’s foreign intelligence agency, expanded its network of human sources within the group, according to 10 current and former American and Israeli officials. Specifically, Mossad recruited people in Lebanon to help Hezbollah build secret facilities after the war. Mossad sources provided the Israelis with information about the locations of the bunkers and helped monitor them, two officials said.

The Israelis generally shared intelligence on Hezbollah with the United States and European allies.

A key moment came in 2012, when Unit 8200 obtained a trove of information about the locations of Hezbollah leaders, their hideouts, and the group’s missile and rocket batteries, according to five current and former Israeli and European defense officials.

In the years since the 2006 war, Israeli spy agencies have refined the intelligence gathered from the previous operation to produce information that could be used in the event of war with Hezbollah. “According to Israeli defense officials familiar with the intelligence, when the 2006 war ended, Israel had a target bank of nearly 200 Hezbollah leaders, operatives, weapons caches and missile sites. By the time Israel launched its campaign last September, there were tens of thousands,” he said.

Turning pagers into killer devices

To gain an advantage in a potential war with Hezbollah, Israel also made plans to sabotage the militia from within. Israel’s Unit 8200 and the Mossad embraced a plan to supply Hezbollah with booby-trapped devices that could be detonated at a future date, according to six current and former Israeli defense officials, the newspaper reported.

Within the Israeli intelligence community, the devices were known as “buttons” that could be activated at a moment of Israel’s choosing. The buttons were relatively simple to design and produce, and Israeli engineers had mastered placing PETN explosives inside electronic device batteries, turning them into small bombs.

The most difficult operation was undertaken by Mossad, which tricked the group for nearly a decade into purchasing military equipment and communications equipment from Israeli front companies.

In 2014, Israel seized an opportunity when Japanese tech company iCOM stopped producing its popular IC-V82 walkie-talkies. The devices, originally assembled in Osaka, Japan, were so popular that knockoffs were already being made across Asia and sold on online forums and in black market deals.

Unit 8200 discovered that Hezbollah was specifically looking for the same device to equip all of its forward-deployed forces, according to seven Israeli and European officials. They even designed a special vest for their troops with a chest pocket specifically designed for the device. Israel began making its own versions of the walkie-talkies with minor modifications, including packing explosives into their batteries, according to eight current and former Israeli and American officials. The first Israeli-made versions arrived in Lebanon in 2015—and more than 15,000 were eventually shipped, according to some officials.

In 2018, an Israeli Mossad intelligence officer drafted a plan that would use similar technology to plant explosives in a pager battery. Israeli intelligence chiefs reviewed the plan but decided that Hezbollah’s use of pagers wasn’t widespread enough, according to three officials. The plan was shelved, the newspaper said. Over the next three years, Israel’s growing ability to hack cellphones left Hezbollah, Iran and their allies increasingly wary of using smartphones. Israeli officers from Unit 8200 helped stoke the fear, using bots on social media to push Arabic-language news reports about Israel’s ability to hack phones, according to two agency officers.

Fearing that smartphones could be compromised, Hezbollah’s leadership decided to expand its use of pagers. These devices allowed them to send messages to fighters without revealing location data and did not contain cameras and microphones that could be hacked.

According to eight current and former Israeli officials, Hezbollah began looking for pagers powerful enough for combat. Israeli intelligence officers reconsidered the pager operation, building a network of front companies to hide their origins and sell products to the militia. The Israeli intelligence officers targeted a Taiwanese brand, Gold Apollo, known for its pagers.

In May 2022, a company called BAC Consulting was registered in Budapest. One month later, in Sofia, Bulgaria, a company called Norta Global Ltd. was registered for a Norwegian citizen named Rinson Jose.

BAC Consulting bought a license from Gold Apollo to manufacture a new model of pager known as the AR-924 Rugged. It was bulkier than the existing Gold Apollo pagers, but was promoted as waterproof and had a longer battery life than competitors.

Mossad oversaw the production of the pagers in Israel, according to Israeli officials. Working with middlemen, Mossad agents began marketing the pagers to Hezbollah buyers and offered a discounted price for bulk purchases.

The Mossad presented the device, which contained no hidden explosives, to Netanyahu during a meeting in March 2023, according to two people familiar with the meeting. The prime minister was skeptical about its durability and asked Mossad chief David Barnea how easily it would break. Barnea assured him it was sturdy.

Conduct war games

The appeal process was not fully ready in October 2023, when Hamas-led attacks sparked a fierce debate within the Israeli government about whether Israel should launch a full-scale war against Hezbollah.

Some, including Defense Minister Yoav Galant, argued for striking Hezbollah, which began firing rockets into Israel on October 8, 2023, in solidarity with Hamas. He said it was an opportunity to deal with Hezbollah’s “difficult enemy” before turning to what he saw as Hamas’s less difficult enemy, according to five Israeli officials familiar with the meetings.

The newspaper claims that "after a phone call with President Biden on October 11, 2023, Mr. Netanyahu, along with his newly formed war cabinet, decided for the time being not to open another front with Hezbollah, effectively ending a high-level discussion on the subject for several months."

Even as Israel focused on Hamas, military and intelligence officials continued to refine plans for a possible war with Hezbollah.

Israeli intelligence analysts, who had been constantly monitoring the devices’ use, spotted a potential problem with the operation. At least one Hezbollah technician began to suspect that the walkie-talkies might contain hidden explosives, according to three Israeli defense officials. Israel quickly responded to the matter this year, killing the technician in an airstrike.

For about a year, Israeli intelligence and the air force also ran about 40 war games built around killing Mr. Nasrallah and other top Hezbollah leaders, two Israeli officials said. They wanted to be able to target them at the same time, even if they weren’t in the same place.

“Along the way, Israel has gathered mundane and intimate details about Hezbollah leaders, including the identities of the four mistresses of Fuad Shukr, a founding member of Hezbollah who the U.S. government has long identified as one of the planners of the 1983 Beirut barracks bombing that killed 241 U.S. Marines,” the newspaper reported. “Sometime this year, feeling uncomfortable with his status, Fuad Shukr asked Hezbollah’s top cleric for help in marrying the four women, according to Israeli and European officials. The cleric, Hashem Safieddine, arranged four separate wedding ceremonies over the phone for Fuad Shukr,” the newspaper reported.

"use it or lose it"

Following the exchange of attacks between Hezbollah and Israel, according to the newspaper, the debate within the Israeli government about opening a “northern front” against Hezbollah has been renewed. The Israeli army and Mossad have drawn up different strategies for a campaign against Hezbollah, according to four Israeli officials.

In late August, Barnea, the Mossad chief, wrote a secret letter to Netanyahu, according to a senior Israeli defense official, calling for a two- to three-week campaign that would include eliminating more than half of the group’s missile capabilities and destroying facilities about six miles from the Israeli border. At the same time, senior military officials began their own efforts to pressure Netanyahu to intensify the campaign against Hezbollah.

New intelligence disrupted the planning. Hezbollah operatives began to suspect that the pagers might be sabotaged, according to several officials. On Sept. 11, intelligence showed that Hezbollah was sending some pagers to Iran for testing, and Israeli officials knew it was only a matter of time.

At the time the pagers went off, Renson Jose, a Norwegian who was the head of a Mossad front company, was attending a technology conference in Boston. Within days, Jose was identified in news articles as a participant in the operation, and the Norwegian government announced it wanted him returned to Norway for questioning. But Israeli officials secretly pressed the Biden administration to ensure that Jose could leave the United States without returning to Norway, according to an Israeli official and an American official.

The newspaper says that Israeli officials did not reveal Jose's location, only saying that he was in a "safe place."

Assassination approval

After the pager operation, the Netanyahu government, supported by senior Israeli defense officials, opted for all-out war, a campaign marked by a series of escalations.

The day after the pager bombing, September 17, the Mossad blew up the walkie-talkies, most of which were still in storage because Hezbollah leaders had not yet mobilized fighters for battle against Israel.

In all, dozens of people were killed by the pager and walkie-talkie explosions, including many children, and thousands were injured. Most of the victims were Hezbollah members, which spread chaos among the group's top leaders.

Days later, on September 20, Israeli aircraft bombed a building in Beirut where leaders of Hezbollah's elite Radwan Force were meeting in a hideout, killing several of them along with Ibrahim Aqil, Hezbollah's head of military operations.

On September 23, the Israeli Air Force launched a major campaign, hitting more than 2,000 targets that were targeting Hezbollah's medium- and long-range missile stores.

The most important decision remained: whether or not to kill Mr. Nasrallah.

While senior Israeli officials were arguing, intelligence agencies received new information that Mr. Nasrallah was planning to move to a different hideout, one that would be extremely difficult to hit, according to Israeli defense officials and a Western official.

On September 26, as Netanyahu prepared to travel to New York for the UN General Assembly, the prime minister met with his top political, intelligence and military advisers to discuss approving the assassination. They also had to decide whether to inform the Americans in advance.

Netanyahu and other senior advisers opposed notifying the Biden administration. They believed that American officials would resist the strike, but that regardless, the United States would come to Israel’s defense if Iran retaliated.

Netanyahu approved the assassination the next day, after landing in New York and just hours before he was to take the stage at the United Nations.

In his speech, he spoke about Hezbollah’s grip on Lebanon. He told the assembled heads of state and government: “Do not let Nasrallah drag Lebanon into the abyss.”

Shortly after, Israeli F-15s dropped thousands of pounds of explosives over Beirut that killed Nasrallah.