How to catch spies?

[Gelondil]

In my current game, I'm having a lot of trouble catching enemy spies in my territory. They keep sabotaging my oil production. I have a spy parked on each of my 2 oil deposits, and another halfway between to run to each spot in an attempt to catch someone passing between them. Even still, I've had the oil sabotaged right out from underneath me about 5 times now.

Is there any way to stop them, or will I be forced to take drastic measures?

[mutax2003]

The more military units you have on the tile, the higher the chance that you will catch the spy. So what I usually do is put 10-15 obsolete units and a spy on the oil-well (or aluminum, or uranium), and never have problem with sabotage on that tile afterward. Also, remember to park spies in key space project cities, otherwise it would be a big loss if enemy was somehow able to sabotage your Apollo project.

[KeiserSose]

another question about spies from a person new to the game.

They get to sabotage the enemy 4 times, right? Then what? Is there a way to recharge them? or are they done after 4 uses?

[Quillan]

No sabotage limit. You can sabotage one per turn with each spy, as long as you have the money to pay for it, which is the big thing. Sabotaging an improvement (can't do roads, just things like mines/wells/cottages/etc) only costs a couple hundred, but sabotaging production in a city is expensive. It seems to be based on how many hammers have already been completed, but I've seen 3000+ sabotage costs on wonders that are near completion.

[Gelondil]

aaah, excellent, thanks for the reply mutax, that'll help a lot.

[proviisori]

and 4 is the number of spies you can have IIRC