You may want to redo the US flag icon. The first thing I thought when I saw it was that I was looking at the Chilean flag. I think that by trying to conceptually simplify the icon, you may instead just be running the risk of creating confusion.
Also, rather than using flag icons in general, you may want to consider representing this information some other way. In my experience, choosing certain flag icons can have highly political ramifications with certain groups. For example, what would you do with a journal from Taiwan/ROC? (hint: you can choose between offending mainland Chinese, Taiwanese Chinese, members of the Chinese diaspora, or all three groups at the same time)