Exactly. WarGames is very similar to a true incident that occurred in 1979, four years before the release of the film.

https://blog.ucsusa.org/david-wright/nuclear-false-alarm-950...

    In this case, it turns out that a technician mistakenly inserted into a NORAD computer a training tape that simulated a large Soviet attack on the United States. Because of the design of the warning system, that information was sent out widely through the U.S. nuclear command network.