User blog comment:Rassilon of Old/Young Justice spoilers at Comic-Con 2012/@comment-108.89.213.126-20120717013346/@comment-4454131-20120717214556

Atlanteans are from earth so they don't count as aliens. I'm not sure if they meant new aliens we haven't seen in season 1 yet but there's also the reach and we'll probably see more apocoliptans.