Colossus: The Forbin Project (1970)

 Colossus: The Forbin Project (1970)

Forbin is the designer of an incredibly sophisticated computer that will 

run all of America's nuclear defenses. Shortly after being turned on, it 

detects the existence of Guardian, the Soviet counterpart, previously 

unknown to US Planners. Both computers insist that they be linked, and 

after taking safeguards to preserve confidential material, each side 

agrees to allow it. As soon as the link is established the two become a 

new Super computer and threaten the world with the immediate launch of 

nuclear weapons if they are detached. Colossus begins to give its plans 

for the management of the world under its guidance. Forbin and the other

 scientists form a technological resistance to Colossus which must operate 

underground. (John Vogel IMDB)