Colossus: The Forbin Project

Colossus: The Forbin Project is a movie starring Eric Braeden, Susan Clark, and Gordon Pinsent. Thinking this will prevent war, the US government gives an impenetrable supercomputer total control over launching nuclear missiles. But...
The U.S. has handed over control of its nuclear defense system to the Colossus supercomputer designed by scientist Dr. Charles Forbin. It soon becomes clear, that the now-sentient Colossus is far more intelligent than its creator realized—with the fate of the world hanging in the balance.