So, the linked article says:

Canadian coins containing tiny transmitters have mysteriously turned up in the pockets of at least three American contractors who visited Canada, says a branch of the U.S. Department of Defence.

But another story gets published that says:

Defence contractors had apparently been give certain special-issue Canadian coins, the unfamiliar look of which caused them to be concerned about the money, a source said. That led to an investigation once the contractors returned to the United States.

But a U.S. agency that investigated the complaint found no evidence of any secret transmitters, or of any other tampering.

In other words, they got poppy quarters, decided in their professional paranoia that they were part of some secret plot, and reported them to a security agency which dutifully started an investigation, and apparently a report on the matter presented it as if the suspicions were true. Your tax dollars at work.

Paranoia and suspicion can cause people to jump to stupid conclusions. This is why having a system of checks and balances around law enforcement activities is necessary. You need independent parties that can put a stop to things when people get a little too wrapped up in their own theories...