In Stranger Things season 3, the Russians attempted to open a gate to the Upside Down to weaponize its creatures and gain a strategic advantage over the United States during the Cold War.

Cold War Context

The Soviet Union viewed the Upside Down as a potential source of powerful biological weapons, fearing the U.S. had already accessed it through Hawkins Lab experiments. They captured a Demogorgon—possibly drawn through an existing rift—and aimed to harness monsters like it for military superiority. Their failed initial attempt in Russia prompted a secret operation under Starcourt Mall in Hawkins.

Discovery and Technology

Russians likely detected the Hawkins gate's energy while it remained open post-season 2, using advanced machinery like a "Key" device to generate rifts. This mirrored U.S. efforts but escalated into an arms race for interdimensional control. The mid-credits scene shows their success in containing a Demogorgon, hinting at further plans.