How does the Counter-Espionage within my own borders work? (see pic)

http://img258.imageshack.us/img258/3937/cecd3.th.jpg (http://img258.imageshack.us/my.php?image=cecd3.jpg)

Your spies have a chance of catching enemy spies in their vision radius. So if an enemy spy moves adjacent to one of your spies, there's a chance you'll catch him. That's what the tip is telling you about. Leave spies in your borders to catch spies.

In that instance, I believe it is referring to a domestic spies' effect of seeing/outing foreign spies, not to the Counter Espionage mission.

ohhh, ahhh
thx a lot!