Answer: because they feared those strikes were linked with the worldwide Communist revolution being fomented in the Soviet Union.
Step-by-step explanation:
Consumer prices continued to rise after the war, and discontented workers, released from wartime constraints, were more willing to go out on strike for their demands. In 1919, more than 4 million workers participated in 3,600 strikes against management. Most of the workers sought nothing more than higher wages and shorter workweeks, but their critics linked them with the worldwide Communist revolution. Some workers in the East won their demands early in the year, but after a general strike in Seattle, public opinion began to turn against labor’s demands.