The Soviet Union opened its first McDonald's restaurant in 1990.
The restaurant opened in Moscow on January 31, 1990, near Pushkin Square. Its arrival became a major international branding event because it brought a highly recognizable American fast-food chain into the Soviet capital during the final years of the Soviet state.
The project required extensive preparation, including sourcing and developing ingredients within the Soviet Union. Thousands of customers attended the opening, and the restaurant quickly became associated with both consumer culture and the changing political atmosphere of the period.
The answer is the Soviet Union rather than Russia because the opening occurred before the Soviet Union dissolved in 1991. Modern McDonald's restaurants in Russia belonged to a later national operation and should not be used as the name of the country at the time of the opening.