Comment by Tycho
Consider the illegal immigration question. Tens of millions of people are in the country, knowingly in violation of the law. Many foreign criminal gangs are operating in the country. Yet the federal government was prevented from even constructing a simple wall to stop the situation getting worse. Not only that, but other authorities in the country are even declaring “sanctuary cities”, openly contravening the efforts of federal law enforcement. Latest thing we hear is district judges harbouring illegal immigrant gang members in their home. We are at a point of complete absurdity. So, yes, invoking the “Alien Enemies” act is quite reasonable, given the circumstances. We are not starting from a point of normality.
Consider that the cure "first deport then ask, if at all" will be worse than disease. Not even Nazi Germany had such indiscriminate approach. They marked people first (yellow stars, pink triangles) and then deported them. Trump administration is incapable even of that.