Unfortunately that’s not usually the first impact of terrorism. Support for them will rise until they do something stupid, pointless, and tragic. Unfortunately by that time there’s thousands of people deep in the ideology in an area and it requires military action to clean up. Telling that something is wrong and we’re all hurting brings people in. Killing innocent people drives people away. It’s why David Duke is all rhetoric and little action. He can publicly sever himself and the movement from people who do take action while influencing them to do so and advancing his political position.