simply make it be a virus that's not one birds can get so flu is obviously out.
Do you have any idea how much it costs to engineer a virus?
Seriously, this is a stupid idea, too much that can go wrong or too expensive - if we're going to use a horrific weapon that will make the entirity of the world hate us, why not just use nukes? Or hell, why not just carpet bomb the place?
Though given the great job those hispanic guys did on putting in new carpet in our house yesterday, I don't think I want you to destroy Cuba.