Why were japanese-americans sent to internment camps during world war ii?

As a reaction to the attack on Pearl Harbor in 1942, President Roosevelt authorized Executive Order 9066, by which Japanese-Americans were deported and incarcerated in the interments camps. They were viewed as a threat to national security.

There was a fear that the Japanese would attack the West Coast, that some who lived in the US while may not have ever been to Japan would help them becoming an enemy. They took them out of their homes, their belongings were lost or trashed, they lost their vehicles, their businesses. They were there for years in areas that were horrible and never received proper restitution for what they went through.