I doubt that it will ever happen, but on the talking head channel they were bouncing around the idea of expelling the rest of an attacker's family when they all come over on a visa like he / they had. The idea is that it would be a deterrent to a would be attacker to know that his wife and kids would not be able to stay in this wonderful country that he hates so much, once he would be caught / killed. And, who knows, they are likely of the same mindset anyway, so we should not want them. Is it fair to the maybe unknowing wife and kids? No. But this is war, and you don't take chances with people in war. If there is the slightest chance they are a threat, you get rid of them. Of course, a policy like this would make leberals' heads explode.
I think Israel has a similar policy: You get caught being a terrorist, they bulldoze down your family's house.