It was one of the classics of the Cold War. The strange thing is, that the scenario is just as likely now. There are more nuclear countries than when the original was written and the movie was made.
With the proliferation of disinformation on all sides and the ability to hack into supposedly secure communication systems, who is to say some rogue operative, or even a government, can’t send an order to a unit that isn’t under their command?
How would the unit even know it was an illegal order if it came in the approved channel with the appropriate code words?
When I was in Special Operations we often had no-notice alerts to test our readiness. We had to have our gear ready in our team room. Rucksacks were packed to go. As you can expect these never happened at 9 am on Monday morning.
We’d grab out weapons and gear and head to the airfield. Load onto a C-130 and head out. Was it real? Was it an exercise?
I took that idea and expanded on it for Dragon-Sim 13; not the greatest title, but it stands for a training simulation exercise for a team from Det-K in Korea; the forward based Special Forces unit based in South Korea. I lived for a while there studying martial arts and also occasionally called to active duty tours as needed.