The stunning, simultaneous attack on thousands of Hezbollah terrorists by detonating their pagers had all the hallmarks of a highly complex covert operation — the kind that only Israel’s Mossad would have the means and motive to pull off, experts told The Post.

About 2,800 people were injured and nine others — including a child — were killed Tuesday in Lebanon and Syria — with the vast majority of victims appearing to be military-age men.

The simultaneous, dramatic explosions were shared in viral videos that spread online – but just how did they do it?

“This reeks of a planned IED event,” fire investigation expert and Jensen Hughes senior engineer Jerry Back told The Post on Tuesday.

“The fact that you had multiple events all occurring at the same time, it sounds to me like there were little explosive devices that were built into the equipment, that somebody was trying to light a lot of fires at once, and it had to be that somebody tapped into the manufacturing process,” he said.

The affected devices were from a new shipment that the group received in recent days, and several people noticed their devices warming up before they detonated, a Hezbollah official told the Wall Street Journal on Tuesday. 

The most likely scenario suggests that perpetrators tampered with the shipment either en route to its destination – or by an Israeli sympathizer hiding among Hezbollah’s ranks – due to the devices coming from the same source.

An unnamed insider told Sky News Arabia that Mossad intercepted Hezbollah’s communication devices before they were handed over to the terrorist group, slipping in the highly powerful Pentaerythritol Tetranitrate (PETN) plastic explosive commonly used for military and demolition purposes.

“Mossad placed PETN explosives on the batteries, which were detonated by increasing the temperature,” the source told the outlet.

Center for Strategic Studies’ Middle East program director Jon Alterman said the basics of the Sky Arabia report seem to fit with the facts. “Israel seems to have penetrated their supply chain,” he said.

“That raises doubts in Hezbollah of what other supply chains [Israel has] penetrated, and to what effect.”

Back said the remote detonation reminded him of improvised explosive devices (IED) deployed by insurgents and terrorists in Iraq and Afghanistan.

“They basically modify a cell phone into an explosive device, where they actually put in an energetic material – like C4 or something like that – and they would place them along the sides of the road,” he said. “When they saw a US military vehicle going by, they would call the phone and it would blow up.”

Though it remains unclear what exact mechanism detonated the blast, Back said that one thing is certain: the act was deliberate and planned, as the odds of a single lithium battery spontaneously exploding is roughly one out of every one to 10 million.

“It would defy physics and probability to have them all go off at once,” he said. “We’re talking a terrorist attack that somebody’s trying to use these devices to start fires.”