This indicates that we could remove ALL NATIVES, CITIZENS, DENIZENS, OR SUBJECTS OF THE HOSTILE NATION OR GOVERNMENT" not just the ones invading, but all the ones already here that are unnaturalized. Read it again:  "...all natives, citizens, denizens, or subjects of the hostile nation or government, being of the age of fourteen years and upward, who shall be within the United States and not actually naturalized, shall be liable to be apprehended, restrained, secured, and removed as alien enemies."