I'm pretty sure some of the air traffic controllers for military airfields in WWII were draftees, just like many air defense operators were draftees before the military became an all-volunteer force in 1973.

We know from the PATCO strike there is a pool of spare ATCs, including "military controllers, and retired personnel who temporarily returned to service". https://en.wikipedia.org/wiki/1981_Professional_Air_Traffic_...

Thus, retired civilian personnel is a possible draft pool for a skilled job like ATC which require passing a lot of exams.

That pool is small, certainly, but it was enough to break PATCO.

If the recent news about moving lots of soldiers from EU Nato installations back home is true, they'll have a ton of trained active military ATC's available to use in the US soon.