Colossus- The Forbin Project

Sci-fi thriller directed by Joseph Sargent. When Dr. Charles Forbin (Eric Braeden) creates a super computer capable of controlling America's nuclear defences, it detects the presence of its previously unknown Russian equivalent, and insists on being linked to it.

But when the two machines are switched on they immediately take control, merging into one even stronger super computer by the name of Colossus, issuing its own demands for the Earth's management, and ruthlessly putting down any signs of dissent. With Colossus gaining more power daily, and threatening world destruction if its demands are not met, Forbin secretly enlists the help of other scientists to form a resistance group aimed at restoring normality.