Since "the war on terror" (read the war of terror) has been waged by states, Western and non-Western, for the last 15 years, it is this Terror that is the main terrorism, with its different features, which breeds more terrorism and makes it endless.
"Endless War? Hidden Functions of the 'War on Terror'" (Pluto Books 2006) by David Keen. Keen explores how winning war is rarely an end in itself; rather, war tends to be part of a wider political and economic game that is consistent with strengthening the enemy. Keen devises a radical framework for analysing an unending war project, where the "war on terror" is an extension of the Cold War. An interview.