Terrorism and civil war are tactics and tools that are used by non-state actors in order to achieve political goals. There are different opinions on the relationship between terrorism and civil war. Some authors consider the two as related as water and ice, stating that they encompass different types of violence occurring under different conditions and in different forms. For others, terrorism and civil war are overlapping issues, and this overlap depends upon the timespan and place. The strategy of terrorism can simultaneously take place in a series of worldwide conflicts, in regions where internal war is occurring or persisting. As a matter of the fact, having become the most important problem on the agenda of international society, ISIS (the Islamic State of Iraq and the Levant) is the most concrete example of a structure which uses a sophisticated configuration jointly employing the strategy of insurgency and terror during an internal war. The strategy applied by ISIS can be seen as a modern strategy of insurgency and thus differentiates itself from earlier types of insurgency. It seems that this modern strategy will be used in the future by several actors as a weapon of the poor.