Although I'm not a copyright laywer, I did previously work for an intellectual property services company. The country codes collection is a service they provide designed to make it easy to keep country codes up to date. This doesn't negate the "free-of-charge use" of the database. ISO appear to have clarified this almost 20 years ago: http://xml.coverpages.org/ISOReaffirms.html , and it looks like the situation hasn't changed.

I don't see how your rights would be limited by including it in your app. You can just say the copyright to the ISO database belongs to ISO, but is free-of-charge, and the copyright to the code written by you belongs to you, which is not free of charge, or any license you wish.

Edit: Because I can't reply - CC0, a public domain - like license was released in 2009, well after the clarification of their "free-of-charge use" license.