Laser spying: is it really practical?

Government sources said conversations about Snowden leaks could have been monitored by foreign agents

Among the reasons government sources gave for demanding the return – or destruction – of the Snowden files held by the Guardian at its London offices was that foreign agents could monitor conversations in the room – using lasers.

Assurances that the computers holding the files were disconnected from any networks, and had never been connected to the internet, were not enough to ease GCHQ concerns that the discussions around them could be heard.

How practical is that, though? During the meetings leading up to the destruction, one intelligence agency expert said that if there was a plastic cup in the room, a laser trained on it would be able to pick up the vibrations caused by conversation, and so eavesdrop on them. Or a laser (using non-visible light) could be bounced off a window of the room.

Aficionados of spy films may nod appreciatively: the idea of "laser spying" is a well-known one. It has actually been used by the US against Russian embassies, and has existed as an idea since the 1940s – predating the laser, which was only developed in 1960. A high-quality laser can fire a beam of invisible light for up to half a mile without spreading.

It has even been reported that the CIA used a "laser microphone" to determine that a building in Abbottabad contained a previously unseen male inhabitant – eventually determined to be Osama bin Laden. John Pike, director of GlobalSecurity.org, told NPR in May 2011: "If you shine a laser beam on those windows [of the buildings], you can detect those vibrations, and using voice identification, you can figure out how many different voices are speaking in each of the rooms of the compound."

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http://www.theguardian.com/world/2013/aug/22/gchq-warned-laser-spying-guardian-offices