The acoustic kitty was a project launched by the CIA in the 1960s. They attempted to use a cat in spy missions. Some of their targets were the Kremlin and the Soviet embassies.
A battery and a microphone were implanted in the cat along with an antenna in its tail. It would have allowed the cat to record information and sound from its surroundings inconspicuously. The problem was that the cat would get hungry and get distracted because of it. To fix the issue, they put it through another surgery attempting to correct its behavior.
The Surgical and training expenses were estimated to have been up to $20 million. The first mission for the cat was to eavesdrop on a conversation between two men in a park outside of the Soviet compound on Wisconsin Avenue in Washington D.C.
The cat was released nearby, but hit by a taxi cab and killed almost instantly. All other tests after that failed. Soon after the project was declared a total loss and was completely cancelled by 1966.