I think concentration camps is a fit epithet to denote the mass detention centers of ICE on several scores. In the first place, it means according to the Oxford English Dictionary:
concentration camp, n.
2. a. A camp in which large numbers of people, especially political prisoners or members of persecuted minorities, are deliberately imprisoned in a relatively small area with inadequate facilities, sometimes to provide forced labour or to await mass execution.
And in the second place, it is appropriate and good to evoke Nazis and their past atrocities in the context for reasons already covered here. That is a powerful specter, and if ever there were a time fit to call on its warning for the sake of the present, it is now. That is, so long as it is not casually tossed off but meant in earnest and scrupulously applied. Methinks. If only I could add to this, but am called away.