[wakawaka28]

I think it's de facto required to be a US citizen (and preferably by birth) in more jobs than you think. It makes lots of sense. We have had scientists come from other countries to infiltrate our nuclear program, and we may not have even caught them all. This type of espionage is expected, and it is righteous to stop it. "Discrimination" or not, it is entirely reasonable for nationality and background to rule people out for any nationally sensitive job. I don't think you can find any country outside the West where the legitimacy of this criterion is questioned on the basis of fairness.