United States Executive Order 9066 was signed into law on February 19, 1942, by Franklin D Roosevelt, utilizing his authority as Commander in Chief to exercise war powers.
This order allowed military commanders to declare areas of the US as military areas, and regulate them. This included rights to enter, remain, and leave. It was eventually applied to 1/3 of the US and was used against those with "Foreign Enemy Ancestry" even though they were native born US citizens.
The Secretary of War was to assist those residents of such an area who were excluded with transportation, food, shelter, and other accommodations. Those of Japanese ancestry were the only ones who received such "aid", those of German and Italian descent were left to fend for themselves.