I think there is another fact to be looked at here...

I imagine most would agree that the bad guys dont think/act rationally.

A Mcdonalds as a symbol for the USA, or recently a German bakery in India

So, after the event, it is known that Germans, French, Australians etc. Killed the bad guy...

If by some small chance there was a crazy in the ranks of extremists (Could very well be ;-) then there could have been a very good chance that somewhere in the world a German, French or australian tourist could have been made to pay the price.

Of the top of my head, i cannot remember a US passport being used... and there are plenty of older US passports in circulation, and pretty easy to fake..

Now, what nation could mount an operation like this... AND be so reliant on the USA that they would not dare using a US passport?

Anyway, whoever did it took into account and ignored the possibility of retribution against the citizens of the passports used....

Best
Chris