How The US Uses Its Embassies to Intercept Allied Countries’ Phone Calls

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On Sunday night, Glenn Greenwald published another revelation about the US spying on an allied European country - Spain, this time. But what you might’ve missed was an explanation of how this is even possible.

After all, in the US, the NSA can rely on the law to compel phone companies to share communications with them. That won’t work in Spain or Germany. So how do American spies intercept friendly communications abroad?

Der Spiegel published a story last night alleging that the US Embassy in Berlin doubles as a listening station for German phone calls. Apparently, this is true of many of the US embassies in allied countries. Journalist Duncan Campbell has a post explaining how this works. It looks like something out of a conspiracy theory.

The key visible feature of most embassy and diplomatic sites that give away their secret spying missions are large windowless areas on top floors, and also sheds or hangers on the roof which are designed to look as though they might contain lift or air conditioning apparatus.

At the US Embassy in Berlin, the lighter coloured panels on the south west, north west and northeast corners of the rooftop surveillance facility are dielectric "radio windows" which allow all types of radio signals to reach collection and analysis equipment on the roof and floor directly below.

The "radio window" panels are made of special material which does not conduct electricity.   That is so weak radio signals coming in from all corners of the city are not diminished (attenuated) as they pass into the building and reach the sigint (signals intelligence) antennae.

Usually, dielectric window panels for signals intelligence work are made of plastic or fibreglass.   They are often shaped and coloured to look as though they are a normal part of the building, or are special architectural features.   

The spy group responsible for these stations is called the Special Collection Service, they’re a joint CIA and NSA program. The Special Collection Service puts these listening stations in embassies because they’re protected from scrutiny by diplomatic immunity. Campbell says that the US has embassy listening stations all over the place. It’s easy to imagine that changing soon, however, as more of these Snowden leaks continue to trickle out.