A force shield is a defensive support power available to all factions in Command & Conquer: Red Alert 2: Yuri's Revenge.
The force shield is an energy field applied on allied structures in a selected large area, rendering them invulnerable to attack for 25 seconds, much like the effect of the Iron Curtain. However, it uses up the base's entire power supply for 60 seconds. It begins charging up as soon as a battle lab is constructed, and requires that structure to charge further uses.
Unlike the Iron Curtain, it does not affect units, and does not harm infantrymen.
The AI will use Force Shield immediately after an offensive superweapon activation against their primary base. However, the AI will not always use Force Shield in this circumstance; the probability of the AI using Force Shield depends on the difficulty.
On Easy, it will activate Force Shield 10% of the time, 50% on Medium and 90% on Hard.
The AI is able to predict where a superweapon will hit accurately.
The AI will not use Force Shield against a Psychic Dominator activation.