A four-legged robot called BigDog now sports an arm powerful enough to lift and throw breeze blocks.
Made by US robotics company Boston Dynamics, the machine is backed by the Pentagon.
BigDog was designed primarily for military use, and the arm could help soldiers pick up and carry heavy loads.
But one robotics expert said the technology's potential was "enormous" for use in other areas, such as search and rescue.
BigDog is one of several robots created by the Massachusetts-based firm and funded by the US Army Research Laboratory.
