The Day the Earth Stood Still

When a flying saucer lands in Washington, D.C., the Army quickly surrounds it. A humanoid emerges from the spacecraft and announces that he is visiting the earth in peace. When he unexpectedly opens a small device, he is shot and wounded by a nervous soldier. A tall robot emerges from the saucer and quickly disintegrates the soldiers' weapons. The alien orders the robot, Gort, to desist. He explains that the now-broken device was a gift for the President of the United States which would have enabled him "to study life on the other planets".