How were Japanese Americans treated during World War II? Why did some Americans feel this was necessary? Were their fears justified?

Japanese Americans were treated poorly, Roosevelt signed Executive Order 9066, which forced all Japanese Americans to evacuate the West Coast. they thought this was necessary to prevent any further actions from happening at the time and i don't know if their fears were justified.

Japanese Americans where put in camps in some places because it was thought they might try to contact japan and betray America.