Robotic battle suit

Robotic battle suits are a type of mech developed by the United States military. They're also referred to as Walkers.

Fiction

Titan Prime comic

An experimental weapons division under the command of General Rufus "Mad Dog" Madison developed the robotic battle suits as part of a program to combat terrorist organisations like MECH. Unfortunately the US government didn't see the value of the battle suits and shut the program down. Learning of the existence of the Autobots, Madison jumped to the conclusion that a rival department had stolen their battle suit designs, so he took six of the battle suits his division had built, and laid a trap for the Autobots. Though the suits fared well against Optimus Prime and his team, once the Autobots surrendered, Madison discovered that they were not humans in battle suits at all. Mad Dogs & Autobots