Final answer:
The main difficulty in bringing Russian hockey players to the United States was due to Cold War political conflicts, specifically the diplomatic and economic isolation enforced by both countries.
Step-by-step explanation:
Getting Russian hockey players to come to the United States was so difficult primarily due to political conflicts between the two countries during the Cold War. After World War II, the Soviet Union was largely isolated from the rest of the world by the so-called Iron Curtain, and the United States also imposed strict entry limits on Soviet citizens. These restrictions were part of the broader tensions between the two superpowers and their distinct ideological and political stances. Travel outside of the Soviet Union was exceedingly difficult both for its citizens and for foreigners trying to enter the country. Additionally, concerns about cultural differences, such as language barriers and the effect of immigration on a country's culture, may have played a role in the difficulty of bringing Soviet players to the U.S.