Project A119 was also known as A Study of Lunar Research Flights. The project was a top-secret plan created in the 1950s by the US Air Force. The point of the project was to detonate a nuclear bomb on the moon to boost public morale in the US when the Soviet Union took the lead in the Space Race.
It wasn’t until 2000 that the plan was even revealed. Leonard Reiffel the former executive at the National Aeronautics and Space Administration (NASA) led the project in 1958 and was the one who leaked the information. The project was never carried out, luckily. They decided that landing on the moon would be a much better way to spend the money and find more favor from the public than an explosion.
The project was a secret for 45 years before Reiffel revealed it. The US government still does not officially recognize any involvement in the study.