The CIA's Feline Weapon

From Wiki Petey:

Acoustic Kitty was a CIA project launched by the Directorate of Science & Technology in the 1960s attempting to use cats in spy missions. The first cat mission was eavesdropping on two men in a park outside the Soviet compound on Wisconsin Avenue in Washington, D.C. The cat was released nearby, but was hit and killed by a taxi almost immediately. Shortly thereafter the project was considered a failure and declared to be a total loss.

via Wikipedia