I don’t favor deportation for terrorists. If an American did this, it would be treason, even if our officials refuse to acknowledge it. And to release an enemy during war, so they can strike again, seems counterproductive.
We release them anyway. I was at a trial where the Pakistani defendant got 10 years for money laundering (he had turned state’s evidence and got a plea bargain), followed by deportation. The standard practice is to have them serve a sentence and then deport them.
Unless you can be sure they’ll get a really, really long sentence, I think it’s better to just get them out of the country, since it’s getting harder and harder to get a conviction or really punish them in any way.