The Pentagon shelled out a staggering eight figure sum for a weapon believed to be the cause of the mysterious 'Havana Syndrome', insiders say. 

The weapon has been blamed for a series of unexplained ailments impacting US spies, diplomats and military servicemembers for the past decade. 

According to military sources speaking to CNN, the Defense Department has spent more than a year testing the device, which was reportedly purchased in an undercover operation for 'eight figures'.

The device was clandestinely purchased in the final days of the Biden administration and is said to produce pulsed radio waves that penetrate a person's body, according to insiders. 

It has been linked to so-called 'Havana Syndrome', a controversial disease which is yet to be formally recognized but has been put forward as an explanation for dozens of anomalous ailments hitting US officials.

The condition was first documented in 2016, after officials said a localized sound wave caused symptoms including headaches, dizziness, nausea, cognitive impairment, memory lapses, balance issues and insomnia. 

The device was purchased by Homeland Security Investigations (HSI), a division of the Department of Homeland Security (DHS), according to sources.

The weapon contains Russian-made components, although it is not clear where or from whom the device was purchased, insiders said.

Sources said the mysterious device could fit in a backpack, but details over the exact makeup of the weapon remain unclear. 

According to insiders who say they were briefed on the device, investigators have long struggled to understand how the weapon could be so potent and yet still portable, reports CNN. 

Incidents of US officials being struck down by 'Havana Syndrome' are currently classified only as 'anomalous health episodes', and there remains skepticism surrounding links between the incidents.

The 'episodes' first began in 2016 as a number of US diplomats in the Cuban capital of Havana were hit with severe illness. 

In years since, similar cases involving US officials have been reported around the world. 

Russia has often been blamed as the chief suspect and some victims have expressed frustration over a lack of action in proving Russia was targeting and attacking US government officials. 

Former CIA Director Bill Burns vowed to get to the bottom of the unexplained ailments when he took the office in March 2021.