In Metal Gear Solid: Peace Walker, the AI weapon that becomes a major threat is called Peace Walker.
Peace Walker is a nuclear-capable bipedal weapon developed through a secret project in Costa Rica. Its designers intend to create a machine that can make an automated nuclear retaliation decision, removing the emotional uncertainty associated with human commanders.
The weapon is one of several unmanned Metal Gear units encountered during the game. The other major AI weapons include Chrysalis, Cocoon, and Basilisk, while ZEKE is assembled by the Militaires Sans Frontières group.
The name creates an intentional contrast: Peace Walker is presented as a system meant to deter war, yet its nuclear capability and autonomous decision-making make it a profound danger. The game’s story examines deterrence, nuclear strategy, and private military power.