This definitely feels like the show Person of Interest, in which a former CIA guy and a billionare computer hacker try to stop crimes before they happen with the help of an AI (initially built for the government to monitor all traffic and street cams)
Some of them may well be. Without a fair trial, there’s simply no way of knowing.
Even with trials people have been wrongly convicted in the past. Imagine what happens when you have the power to detain people indefinitely without any oversight. Abuses and/or mistakes WILL happen. It’s a certainty.
Sure, many of those people may indeed be terrorists or at least radicals. How many of them have committed a crime? How many are a case of mistaken identity? By all means, try them in court and hang them if found guilty.
This is why Gunatanamo is wrong and history will remember it as horrible thing.