By Josh Margolin

Israel had a hand in the manufacturing of pagers that exploded on Hezbollah operatives this week, with this type of "supply chain interdiction" operation having been planned for at least 15 years, a U.S. intelligence source confirmed to ABC News.

The CIA has long been reluctant to employ this tactic because the risk to innocents was too high, the source said.

Planning for the attack involved shell companies, with multiple layers of Israeli intelligence officers and their assets fronting a legitimate company that produced the pagers, the source confirmed to ABC News, with at least some of those doing the work unaware of who they were actually working for.

People attending a funeral for victims of Tuesday's pager attacks in Lebanon react after an explosion in a store, in southern Beirut, Sept. 18, 2024.

MORE: Israel launches strikes on Hezbollah in wake of device explosions

Israel's hand in the manufacturing was first reported by The New York Times.

One to two ounces of explosives and a remote trigger switch to set off the blast were planted in the pagers, according to the sources.

The last two days of explosions in Lebanon, triggered remotely with explosives inside pagers or walkie-talkies, have killed at least 37 people and wounded 2,931, according to Lebanese Health Minister Firass Al-Abyad.

Hussein Malla/AP

Police officers inspect a car inside of which a hand-held pager exploded, Beirut, Lebanon, Tuesday, Sept. 17, 2024.

AFP via Getty Images

The remains of exploded pagers are seen in Beirut's southern suburbs Sept 18, 2024, after hundreds of pagers used by Hezbollah members exploded across Lebanon on Sept. 17, 2024, killing at least nine people.

The conflict between Hezbollah and Israel grew wider on Thursday, with Israel launching strikes on Lebanon and Hezbollah returning fire.

ABC News has reached out to BAC Consulting -- the Hungary-based company contracted to produce the pagers on behalf of Gold Apollo in Taiwan -- but neither company has responded to our repeated requests.

The pagers were never in Hungary and the company was "a trading intermediary, with no manufacturing or operational site in Hungary," a spokesperson for the Hungarian government told ABC News on Wednesday.

Mohamed Azakir/Reuters

An ambulance arrives to American University of Beirut Medical Center as more than 1,000 people, including Hezbollah fighters and medics, were wounded when the pagers they use to communicate exploded across Lebanon, according to a security source, in Beirut, Sept. 17, 2024.

MORE: Israel-Gaza live updates: Death toll rises from pager, walkie-talkie explosions

In a speech Thursday, Hezbollah leader Hassan Nasrallah said the group's top leadership had old pagers, not the new ones used in the attack, which were reportedly shipped in the last six months. The group has begun a full investigation into the explosions.

"Not all of the pagers had been distributed and some of them were turned off," Nasrallah said.

"Over two days, the enemy wanted to kill at least 5,000 people. ... The enemy knew that the pager devices numbered 4,000," he added.

ABC News' Nasser Atta contributed to this report.

Israel had hand in manufacturing pagers that exploded in Lebanon: Source

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