That movie was called Screamers based on a Philip K Dick short story.packnrat said:there was this si-fi movie some time back, there was a war on another planet were one side built a self powerd and controled device that would track down and kill the other side,
but it got away and started to build some of it's own, much bigger and far better, even got to the point they looked like us
and would attack both sides,
and then found a way to earth.
end of story.