In their advertisements, many employers specify that the applicant should be from a certain nationality or nationalities. What do you say?

Employment discrimination against a national origin group includes discrimination based on:

1. Ethnicity: Employment discrimination against members of an ethnic group. National origin discrimination also includes discrimination against anyone who does not belong to a particular ethnic group.

2. Perception: Employment discrimination against an individual based on the employer's belief that he is a member of a particular national origin group.

Discrimination or not, it is their choice. But more important, instead of finding the best employee for the job, they are limiting their options, which means they have a poor management that is looking for personal comfort instead of performance.

Yes it is!

Definitely, it is a discrimination and indicates that organization has narrow mind. It depends on organizational strategic policy, values, belief, culture and sustainable relationship with other country.

This is of course discriminatory, racist and in some countires punishable by law. It is a question of education above all.

It is not a discriminatory or what it is intended therein, but it is the right and obligation of the Employer to whatever they wanted to be their employees in their companies.

Yes.  Depends upon the country, the employer getting visa or labour permits for a certain nationality only in some cases.  So, it is justifiable.

This should never happen. I'm always voting for equality among all people. It is not a proved fact that certain nationalities are better than the others and it will never will, because this world is so dynamic and all nations are undergoing changes with their education system, cultural system, and technological advancements throughout time, so justifying it with culture and citizenship will only make it more discriminatory in its sense.