How did President Truman act to protect the nation from threats at home? Was this justified?

After world war 1 immigration was based on

As the coach of the u.s. olympic cycling team, i can state without question that the swedish and french teams were using illegal steroids. how else could they have beaten us so badly in the last competition? the u.s. team trained much harder and was much more skilled than our opponents. we only lost because a few teams cheated.

How do you think american life would change greatly, as soldiers went to war in europe?