What event severely strained U.S.-Soviet relations?

1 Answer
Mar 19, 2017

There have been so many.

Explanation:

The Soviet development of the Atomic Bomb, the Cuban Missile Crisis, The Cold War generally, various Middle Eastern Wars, the Korean War, the Vietnam war, the revolution in China, the Berlin Airlift.

As a wild guess you mean the Cuban Missile Crisis in 1962 which was one of the worst. The result guaranteed the independence of the Cuban government. It established the "Hotline" between the Kremlin and the White House.

As a side line in response to the previous answer 14 Allied nations intervened in the Russian Civil War in in various places for many reasons. Concerns began as early as the spring of 1918. Of particular interest was a large number of Czech POWs in Siberia and much war material sent to the former Russian Government during the War. Japanese troops remained in Russian territory until 1922. The Americans left in 1920.

https://en.wikipedia.org/wiki/Allied_intervention_in_the_Russian_Civil_War