I’m not overly convinced that such restrictions are truly necessary at scale. When we are dealing with “large” populations, these sorts of edge-cases begin to become extremely improbable. While they would indeed remain possible, I would argue that if they were to actually end up occurring, that would be as a symptom of a much more serious societal breakdown which would most likely indicate an imminent collapse. That being said, if there was to be some explicit restriction, I believe that it is sufficient to state that individual must be, at least, a naturalized citizen. There could also be some other clause added for the sake of ensuring that the individuals interests are in that of the nation’s – like the natural-born citizen clause in the U.S.A; however, I personally haven’t come to a decision on whether I agree with that, or not.