However, despite the fact that the political and criminal effects of 'terrorism' are frequently and extensively discussed in everyday life, no single universal definition of it has ever been adopted under international law..Nevertheless, the recent developments, such as the terror attacks in the US on 11 September 2001, in the area of international law suggest that making a clear definition of this concept is a necessary prerequisite for mobilizing international support against terrorism and essential to respond to the terrorist acts in an effective way.