Open this photo in gallery: U.S. President Donald Trump speaks to reporters next to Air Force One after arriving back at Joint Base Andrews, Md., on Feb. 2.Ben Curtis/The Associated Press U.S. President Donald Trump said he planned to invoke the Alien Enemies Act as part of his pledge to deport millions of people who are in the country illegally. Below is a look at the act and how it has been used in the past. What is the act? The Alien Enemies Act was enacted in 1798 to combat spying and sabotage during tensions with France. It authorizes the...