This is the U.S. Navy's most secretive submarine

No, the U.S. Navy is probably not using a multi-billion dollar submarine to listen in on your phone calls and emails on behalf of the National Security Agency. But it could.

A long line of secretive Navy spy submarines, most recently a nuclear-powered behemoth named USS Jimmy Carter, have for decades infiltrated remote waters to gather intelligence on rival states' militaries, insurgents, and terrorists on behalf of the NSA and other agencies using a range of sophisticated devices, including special equipment for tapping undersea communications cables.

Before NSA whistleblower Edward Snowden revealed the agency's phone and internet monitoring programs targeting U.S. and European citizens, the mainstream press paid little attention to the elusive, subsurface warship. But following Snowden's disclosures in 2013, several publications including The Huffington Post and the German Der Spiegel speculated that the Jimmy Carter was aiding the NSA's surveillance of citizens' communications in the U.S. and Europe.

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