Swedish corvette HMS Stockholm patrols Jungfrufjarden in the Stockholm archipelago, Sweden, on Monday. Swedish authorities say they've detected "foreign underwater activity" thought to be a possible Russian submarine. Anders Wiklund/EPA/Landov hide caption

itoggle caption Anders Wiklund/EPA/Landov

An Oct. 28, 1985 photo of John A. Walker Jr., being escorted by a federal marshal as he leaves the Montgomery County Detention Center in Rockville, Md., enroute to a federal court in Baltimore. He was ultimately sentenced to life in prison on espionage charges. Bob Daugherty/AP hide caption

itoggle caption Bob Daugherty/AP

The villa that allegedly belongs to the NSA in Vienna. News outlets, the government and opposition parties are battling it out over allegations that the stately villa in a leafy Vienna district served as a sophisticated a U.S. intelligence listening post keeping tabs on most of Vienna. Hans Punz/AP hide caption

itoggle caption Hans Punz/AP