The "Global war on terrorism" has become a widely used expression in the lexicon of Western policymakers, analysts and academics. It causes many controversies and interpretations which are not always helpful in comprehending the essence and logic of this ongoing conflict. First of all, it is necessary to admit that it is indeed a war, where protagonists use violence for political purposes. Having in mind that one of the belligerents is a non-state actor, the most productive way to understand this struggle is to apply a well-established and developed theory of insurgency and counterinsurgency, which until now was mainly used to explain an intra-state armed conflict. The strategic logic of a "global war on terrorism" follows closely the principles of this theory. However, they have to be seen in the context unusual for the insurgency and counterinsurgency theory. Its application at the level of the international system is fraught with challenges and difficulties stemming from the conflict's global and trans-national dimensions.