Hezbollah pager explosions: How could Israel have triggered the deadly blasts?

Nine people, including two young girls, were killed and 2,8000 were maimed across Lebanon today, after hundreds of pagers used by Hezbollah fighters simultaneously exploded across the country. 

The wave of sudden and unexpected detonations, which began around 3.45pm local time (1345 GMT) and lasted roughly an hour, gave way to widespread panic and chaotic scenes across Beirut’s southern suburbs, the Bekaa Valley and southern Lebanon. 

Iran-backed Hezbollah had been using pagers instead of mobile phones because the latter can be tracked and used to pinpoint deadly missile strikes on its commanders. 

David Kennedy, a former US National Security Agency intelligence analyst, told CNN:  'It’s more likely that Israel had human operatives… in Hezbollah… The pagers would have been implanted with explosives and likely only to detonate when a certain message was received. 

'The complexity needed to pull this off is incredible. It would have required many different intelligence components and execution. 

'Human intelligence (HUMINT) would be the main method used to pull this off, along with intercepting the supply chain in order to make modifications to the pagers.'

No one has yet claimed responsibility for the mass incident, though Hezbollah and Lebanon's government has pointed the finger at Israel, which hasn't yet commented. 

There are currently two main theories as to how the detonations happened.

One suggests that the pagers were filled with explosives, and set off by remote access and the other theory proposes a cybersecurity breach caused the pagers' lithium ion batteries to overheat and explode.

A source close to Hezbollah claimed that the incident came as a direct result of an 'Israeli breach' of its communications, though this has not been confirmed.

A different official said that the cause of the explosions was likely the lithium batteries that power the pagers.

While lithium-ion batteries are commonly used in consumer electronics, they can overheat and catch on fire - even exploding violently in some cases. 

This is due to a phenomenon called thermal runaway, a chemical chain reaction which occurs when the battery experiences a rapid temperature change, which is triggered when the battery is overheated, punctured or overcharged.

As this chemical reaction progresses it can lead to a sudden release of energy which can cause devices to explode with intense force and heat.

Lebanese military sources have suggested that the devices were detonated as part of an Israeli attack. 

It is possible that Israeli forces or some other actor could have hacked these devices and remotely overcharged the battery, triggering a thermal runaway.

Pagers often use unencrypted communications channels and outdated software, making them extremely easy targets for an attack.

One-way pagers are passive receivers and so cannot be tracked, but when a message is sent it activates every pager transmitter in the area.

By hijacking the broadcast signal, an adversary could have conceivably infected every single pager on the network simultaneously. 

A virus could have been implanted into the Hezbollah pager network and allowed to remain dormant on the devices until it had spread widely.

This malware may have been remotely triggered or activated on a pre-programmed timer.

Video shows that the devices appeared to receive a message moments before the devices detonated.

This signal could have been the trigger for the explosion or it may have been used to ensure that the fighters were holding the devices when they exploded.

If these explosions are the product of a cyberattack then this is an exceptionally rare case of cyberwarfare causing disruption to physical infrastructure.

Earlier this year, Hezbollah's leader Hassan Nasrallah urged members of his organisation to revert to using the pagers for vital communications, reasoning that modern smartphones would be more susceptible to cyber attacks by Israeli forces. 

But just like mobile phones and many other consumer electronics, pagers also rely on rechargeable lithium batteries to function.

The battery fires can burn up to 590 degrees Celsius (1,100 F) when ignited.

Israel has used this method in the past, most notably to kill Hamas' chief bomb maker, Yahya Ayyash, in 1996. 

Shin Bet, the shadowy intelligence agency, stuffed Ayyash's phone with 15grams of RDX explosive, as he made a call with his father. 

Though Israel has a longstanding policy to never confirm or deny any of the assassinations it is allegedly involved in, former Shin Bet Carmi Gillon confirmed the story in 2012.