During the Cold War, the CIA launched Operation Acoustic Kitty, an attempt to use cats as covert listening devices. The plan involved surgically implanting microphones and transmitters into felines, hoping they could inconspicuously eavesdrop on Soviet conversations.
Unsurprisingly, the project faced numerous challenges, including the cats' unpredictability. The operation was eventually deemed a failure, but it remains a testament to the lengths intelligence agencies would go during the espionage era.