OK, how about if all east german escapees were returned back across the wall because they didnt have visas?
That would be an excellent example, except that was West Germany, who considered East Germans citizens rather than the US. When it comes to immigration, or even refugees, we don't have a great record of distinguishing friends from enemies. As the Obama administration demonstrates both by this policy and their preference for muslim refugees from Syria and Iraq rather than Christians, who ISIS is slaughtering for their faith.