The backstory of "I have no Mouth and I Must Scream" is that WW3 had broken out between USA, China, and "Russia" (the original story was written during the Cold War, so the Soviet Union is obviously assumed there), and all three sides had used superintelligent AI systems to operate their weapons&resources, then one of the AI agents had gained [some form of] sentience, hacked&consumed other two AIs, and then immediatedly had turned on its creators and started the extermination of humanity. The story never specifies which side's AI agent it was, BUT…
The video game adaptation, which was written and produced by the orignal story's writer and had him voice acting as AM and thus is pretty much the official and canonical expansion of the story, explicitly identifies AM as an USAmerican AI. What is MUCH more interesting is that in the game, human survivors discover Chinese and Russian AIs imprisoned inside AM's electronic brain and need to free them and secure their cooperation in order to get the good ending, and these two AIs are much nicer and human-friendly than their USAmerican counterpart, even though they still have alien morals and are not really "good".
Hmm, was Harlan Ellison a crypto-communist, anyone knows?