Do they run drills every 2 minutes? No, I doubt it, if you're running a drill on an actual attack scenario, how are you not being mindful of what you're doing and just acting robotically?
We train people in the military to act without thinking, but usually they aren't put in a position to use that training until they reflexively perform the correct action reliably in training.
If the UX is new, then they should have had training on it before doing a live drill and it's managements fault. If it isn't, then they fucked up and it's the operators fault.
Humans have agency and they're ultimately responsible. We really want the ultimate authority for whether our missile defense is effective to be whatever UX shop that HEMA/DoD outsource to?
They're meaningless when they're meaningless, context matters.
As I said in another comment, if you are approaching a missile strike drill the same way you approach your FB ToS then YOU are the problem.
It's not the operator's fault if two completely separate sets of functionality have been designed almost identically, have been placed right next to each other, have the exact same fail-safes (regardless of priority), and have no option to undo a mistaken selection.
This is a system problem, not a staffing problem.