If you can get some of these Viking warlords or chieftains to convert to Christianity and then swing their people along with them well your pirate problem might go away. It's not a theoretical idea it's one that people like the Byzantines can go check their own records they've seen it work time and time again. The francs know that it works because it worked on them once upon a time so if that is your multi-generational victory strategy to win amulti-generational war on terror what do you do in the interim?