U.S. immigration and military authorities disclosed Monday that immigrants from 27 countries were being held at Guantanamo Bay Naval Station in Cuba, while revealing new details of conditions of confinement and defending the government’s authority to transfer and hold immigrants at the military base.Court filings on behalf of the Homeland Security and Defense departments indicated that 40 immigrants with final deportation orders were being held at Guantanamo Bay as of Friday — with 23 labelled “high risk” and held individually in cells. The remainder were held in another area of special housing for migrants, in groups of up to six.Civil rights attorneys sued the Trump administration this month to prevent it from transferring 10 migrants detained in the U.S. to Guantanamo Bay and filed statements from men held there who said they were mistreated in conditions that of one of them called “a...