What are the anit-espionage measures you can take in Civ 4 BTS? I have one or two spies in all of my cities, especially my older core cities. Yet every few turns, I get a message saying that a spy has been stumbled on in one of those core cities, rather than that spy being caught by my counter-espionage agency. Why? How can I put a stop to these spies? Are my spies just stupid, or am I missing a crucial espionage mechanic?