It's a long-standing requirement of international law. Whenever a foreign national is arrested--including citizen's arrest--the arrestee must be granted access to a representative of his government upon request, his government be notified as soon as practical, and a representative of the arrestee's government must be allowed to interview the arrestor if requested.
You don't get it do you? Screw international law! We're talking about the security of our country and you quote international law? You open border types are getting bolder by the day.
Ya know, if I was the one being "interviewed" by the foreign government, I believe the only thing they would get out of me is, "Get Bent!"