There is.
AdCenter has Target by location, and distribution channels.
You can advertise worldwide if you like, but must choose a distribution channel (most common is English-US). So in essence, if this is chosen, someone in India for example can see your US distribution ad if their browser settings are set to US. If you have English-US distribution channel, and US only targeted, then only those in the US can view the ad.
AdCenter currently has 6 distribution channels in total.
English-US
English-Canada
French-Canada
French-France
English-UK
English-Singapore
I hope that clears it up for you.