How does one go to war with said leader when he is not affiliated with any nation? How does one invade or go to war with a tactic?
Might as well go to war with the
Schlieffen Plan.
The instances of terrorism within the borders of the west have been quite few (especially with in the US). Police your own borders. Work to educate the world.
Diplomacy takes longer than a bomb but it works better in the long run.