Why did FDR Lock up and destroy the lives of over 100,000 Japanese Americans?

What kind of Monster locks up 100,000 Americans who are citizens of America just because they have slanted eyes? FOR OVER 3 YEARS! One of moms dads friends born in America Japanese had a lovely home and wife- FDR Took it from him- put them in camps and his Wife died there! FDR Ruined peoples life and killed people in my opinion.