Allied spies were masters of disguise, capable of impersonating any friendly or enemy infantry, granting them access to the most heavily guarded enemy bases. While inside, spies were able to sabotage infrastructure in a number of ways, such as disrupting a base's power supply, stealing resources from an enemy refinery, or disabling the enemy's high-tech units and production.
In addition, it was standard operating procedure for spies to carry large sums of cash for bribing enemy troops. The spy's innate knowledge of human psychology, coupled with a surplus of foreign currency, makes a persuasive combination that even the most powerful enemy units have difficulty resisting. In practice, spies may cause large numbers of enemy forces to suddenly turn on their former commanders.
However, spies were trained to operate without any conventional weapons and their only defense was to avoid detection. In addition, modern armies have specially-trained units that can detect spies even when disguised. Some of these, such as attack dogs and Sovietwar bears, were also trained to deal with spies in an efficient, if somewhat messy, fashion.
At the cost of $1000 credits, the player can use the spy's Bribe ability to convert all nearby enemy ground units to their cause. Will not work on commandos, heroic units and some other units such as certain naval units.
Production structure: Temporarily disables production
Power structure: Temporarily reduces power to zero, slowing down production and disabling all base defenses and super weapons.
Ore refinery: Steal up to 2000 credits, cannot steal more than what the enemy owns.
Construction Yard and expansion structure: Temporarily disables enemy radar and reveals the enemy's vision.
Technology structure: Temporarily disables all tier 3 units, causes tier 3 aircraft (i.e. Kirov Airships) to crash.