0. We should try to counter the radical ideology by allowing everyone to air their grievances in public without condemning or shouting down those we disagree with. Debate should be welcomed and encouraged not stifled and stigmatised otherwise those with extremist views will still be able to seek out the impressionable and monopolise the narrative they hear.

As I see it this is the most important solution. Trying to catch people just as they are about to commit an atrocity doesn't go anywhere to help solving the root problem. Extremists have been using secure lines of communication for a while and will continue to do so regardless of whether is is decreed legal or illegal and this is to say nothing of offline communication.

You may prevent some fraction of the attempts, but many will be successful and all we will be doing is treating the symptoms whilst probably severely aggravating the cause. No one has their privacy routinely violated and feels more sympathetic to those violating those rights.

We have been involved in a battle of ideas and we need to start formulating a response on this front. Everything else is secondary.