"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..."
http://www.imdb.com/title/tt0064177
"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..."