The NSA is capable of recording 100 percent of a country's telephone calls, according to sources who spoke with The Washington Post. Adding to the intrigue, the Post says it's "withholding details that could be used to identify the country where the system is being employed," implying that this surveillance method is used outside the US. It's also unclear whether the NSA's so-called MYSTIC voice-interception program (yep, that's the emblem above) is actually recording 100 percent of this country's calls, or whether it simply has the ability.

According to the story, the NSA also uses a tool called RETRO to retrieve audio that wasn't deemed suspicious at the time of its original recording. Apparently, RETRO is only used in one foreign country, but documents suggest it could soon be deployed in five more. With the tool, billions of conversations are stored with a 30-day buffer for clearing out the oldest calls as new ones come in.

It's not necessarily surprising that the agency would be reaching into the past as part of its data-collecting efforts, but it's certainly news that it can record and store every single telephone conversation. While we've heard about the NSA collecting call logs in bulk, recording the content of all voice calls is very different than stockpiling metadata.