In an unprecedented security breach, thousands of pagers and walkie-talkie radios belonging to members of Hezbollah detonated across Lebanon in simultaneous explosions on Tuesday and Wednesday, killing at least 26 people and wounding thousands of others.
Hospitals across Lebanon were overwhelmed with an influx of patients after the pager attack on Tuesday, and a field hospital was set up in the southern city of Tyre to accommodate the wounded.
Hezbollah has blamed Israel and vowed to retaliate. Israel has declined to comment on the blasts, but Tuesday’s explosions came just hours after the military announced it was broadening its aims in the war sparked by the Hamas attacks on 7 October to include its fight against Hezbollah along the border with Lebanon.
It remains unclear how exactly such an audacious attack was carried out, but here is what we know so far.
How did the pagers and walkie-talkies explode?
A small amount of explosives were planted inside a new batch of 5,000 pagers ordered by Hezbollah for its members, according to a senior Lebanese security source who spoke to the Reuters news agency. Israel’s intelligence services were responsible, the source said.
“The Mossad injected a board inside of the device that has explosive material that receives a code. It’s very hard to detect it through any means. Even with any device or scanner,” the source said.
Another security source told Reuters that up to 3g of explosives had been hidden in the new pagers and had gone “undetected” by Hezbollah for months. The source said 3,000 of the pagers had exploded when a coded message was sent to them, simultaneously activating the explosives.
An American official who spoke anonymously to the New York Times made similar claims, adding that the devices had been tampered with before they reached Lebanon. Explosive material was reportedly hidden in each pager next to the battery, along with a switch that could remotely detonate the device.
According to the New York Times, the pagers received a message at 3.30pm local time that appeared to have come from the group’s leadership. It was this message that is believed to have activated the explosives. Several videos being circulated of the explosions appear to show victims checking their pagers in the seconds before they exploded.
Fewer details have emerged about Wednesday’s walkie-talkie blasts, but a security source told Reuters that they had been bought by Hezbollah five months ago, about the same time that the pagers were bought.
The Mossad has not commented on either attack.
Where did the devices come from?
The plot appeared to have been many months in the making.
The walkie-talkies are understood to have been bought about the same time as the pagers, and images of the devices examined by Reuters showed an inside panel labeled “ICOM” and “made in Japan”.
ICOM said in a brief statement on its website that it was aware of media reports that walkie-talkies with stickers bearing its logo had exploded in Lebanon. “We are currently trying to establish the facts and will provide updates on our website as new information becomes available,” it said.
The wireless communications company, based in the western city of Osaka, has offices in several other countries, including the US, Germany and China. The firm has previously said that production of model IC-V82, which appeared to be the model in images seen by Reuters, was phased out in 2014.
Hezbollah ordered 5,000 pagers marketed by the Taiwan-based company Gold Apollo, according to the Lebanese official, and it was these new devices that exploded. Other sources told Reuters that these pagers had been brought into the country in the northern hemisphere spring.
Analysts at the open-source intelligence group Bellingcat also identified the pagers as coming from Gold Apollo.
A source close to Hezbollah told the AFP news agency that “the pagers that exploded concern a shipment recently imported by Hezbollah”, which appeared to have been “sabotaged at source”.
A senior Lebanese source told Reuters the devices, identified as the AR-924 model, had been modified by Israel’s spy service “at the production level”.
There is no suggestion that Taiwan-based Gold Apollo was aware its devices had been tampered with. The company’s founder, Hsu Ching-kuang, told reporters on Wednesday that the pagers used in the attack had not been manufactured by Gold Apollo but by BAC Consulting, a company based in Hungary that had the right to use the Taiwanese firm’s brand. However, Cristiana Bársony-Arcidiacono, the chief executive of BAC, told NBC: “I don’t make the pagers. I am just the intermediate. I think you got it wrong.”
Elijah Magnier, a Brussels-based security analyst, told AFP: “For Israel to embed an explosive trigger within the new batch of pagers, they would have likely needed access to the supply chain of these devices.”
Why does Hezbollah use pagers?
A pager is a small wireless device that can receive, and in some cases send, messages but cannot make calls. Popular in the 1980s and 90s, their use quickly declined in the early 2000s with the rise of mobile phones.
Hezbollah is known for using the lower-tech devices to communicate because, unlike mobile phones, they can evade location-tracking and monitoring by Israeli intelligence.
Yossi Melman, a co-author of the book Spies Against Armageddon, said: “A lot of people in Hezbollah carried these pagers, not just top-echelon commanders.”
A security breach of this scale is seen by experts as hugely embarrassing and damaging to morale in the militant group.
“This would easily be the biggest counterintelligence failure that Hezbollah has had in decades,” said Jonathan Panikoff, a former US government deputy national intelligence officer on the Middle East.
Why are mobile phones so trackable?
Hezbollah is well aware of the threat posed by using mobile phones. In February, the group’s general secretary, Hassan Nasrallah, warned supporters their phones were more dangerous than Israeli spies, saying they should break, bury or lock the devices in an iron box.
Mobile phones can be used to track someone’s location because they regularly “ping” masts as they move around, allowing their signal to move to different masts in the network.
“The phone is constantly pinging away to stay in touch with whatever network it is using,” said Alan Woodward, a professor of cybersecurity at Surrey University.
If you monitored the network, you could locate the signal from a specific phone, he said, by seeing which masts were interacting with the device and locating the handset within the overlapping ranges of those masts. In urban areas, the density of masts makes for an accurate zeroing-in process.
“You can do a simple triangulation,” said Woodward.
GPS receivers on phones – used for mapping apps, for instance – also give a device’s location, although you would need to hack your way inside a phone to receive that information.
As a safety move, therefore, Hezbollah turned to pagers, which listen out for a signal from transmission networks in order to receive a message but do not “ping” back. There is no communication made by the pager to monitor, Woodward said.
“You cannot locate the pager because it is doing nothing but listening,” he said.
However, Hezbollah clearly did not anticipate the device itself being used as a potential weapon.
Referring to the walkie-talkie explosions on Wednesday, Woodward said the devices could be tracked because they communicated with each other via radio frequencies, but that tracking was a difficult task and they were not as vulnerable as mobile phones, which may have been why Hezbollah used them. Again, the group did not appear to have suspected that they would be used as explosive weapons.
