 21, which applies only to persons 14 years of age or older who are within the United States and not naturalized.Under this provision, which was first defined and enacted in 1798 (in the Alien Enemies Act, one of the four Alien and Sedition Acts) and amended in 1918 (in the Sedition Act of 1918) to apply to females as well as to males, all "natives, citizens, denizens or subjects" of any foreign nation or government with which the United States is at war "are liable to be apprehended, restrained, secured and removed as alien enemies.