The devices were programmed to beep for several seconds before exploding, according to three of the officials.
Hezbollah has accused Israel of orchestrating the attack but has described limited details of its understanding of the operation. Israel has not commented on the attack nor said it was behind it.
The officials spoke on the condition of anonymity given the sensitive nature of the operation.
Independent cybersecurity experts who have studied footage of the attacks said it was clear that the strength and speed of the explosions were caused by a type of explosive material.
“These pagers were likely modified in some way to cause these types of explosions – the size and strength of the explosion indicates it was not just the battery,” said Mikko Hypponen, a research specialist at software company WithSecure and a cybercrime adviser to Europol.
Keren Elazari, an Israeli cybersecurity analyst and researcher at Tel Aviv University, said the attacks had targeted Hezbollah where it was most vulnerable.
Earlier this year, Hezbollah’s leader, Hassan Nasrallah, strictly limited the use of cellphones, which he saw as increasingly vulnerable to Israeli surveillance, according to some of the officials as well as security experts.
“This attack hit them in their Achilles’ heel because they took out a central means of communication,” Elazari said. “We have seen these types of devices, pagers, targeted before but not in an attack this sophisticated.”
More than 3000 pagers were ordered from the Gold Apollo company in Taiwan, several of the officials said. Hezbollah distributed the pagers to its members throughout Lebanon, with some reaching Hezbollah allies in Iran and Syria. Israel’s attack affected the pagers that were switched on and receiving messages.
It remained unclear Tuesday precisely when the pagers were ordered and when they arrived in Lebanon.
This article originally appeared in The New York Times.
Written by: Sheera Frenkel and Ronen Bergman
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