During the job interview process, is it legal for an employer to ask an applicant what foreign citizenship(s) he holds, if any? In other words, citizenship that is not necessarily relevant to the job (i.e. the applicant has already established his legal right to work where the job is located)
I understand this might be necessary when working for certain companies, for example Lockheed Martin, but are there laws about exactly when it is and when it is not legal?