What was the Western powers' reaction to communism during the 20th century?
The Western powers were largely hostile to communism for most of the 20th century. They saw it as an ideology that was dedicated to overthrowing their way of life and to achieving domination over the entire world.
For these reasons, the Western powers opposed communism for most of the century. When World War I ended, for example, troops from some Western countries were sent to help the White Army in their fight against the communists. During WWII, the West allied itself with the Soviet Union out of necessity. This meant that the Western powers were officially friendly towards communism for a few years. But this led into the Cold War in which there was extreme tension between the West and communist countries.
The Western powers were also typically hostile to communism within their own borders. This was seen clearly in episodes such as the two “red scares” in the United States (early 1920s and early 1950s). Thus, the Western powers were typically quite hostile to communism.