Espionage warnings from the Defense Department caused an international sensation a few years ago over reports of mysterious coins with radio frequency transmitters, until they were debunked. The culprit turned out to be a commemorative quarter in Canada.
But at the height of the mystery, senior Pentagon officials speculated whether Canadians were involved in the spy caper.
"I don't think it is an issue of the Canadians being the bad guys," the Pentagon's counterintelligence chief wrote in an exchange of e-mails obtained this week by The Associated Press, "but then again, who knows."Read MoreSubscribe HereNo Agenda News - Your daily source for the news that matters.