What a stupid article. If you're afraid of a terrorist attack don't dress like American?
There have been terror attacks or plots of one sort of another in France, Spain, UK, Canada, USA, Mumbai, Kenya, Australia, Bali, Belgium, Egypt, the Philippines, Tunisia and a bunch more that I can't remember. Don't dress like any of them either.
Helpful note to Americans: Parading around with a Maple Leaf is not a good idea in the Basque regions of Spain. They have long memories there and still haven't forgiven us for shooting at their fishing trawlers.