Talking about this issue is so lame when most people have not a clue about the real reasons. Thanks to the media and gullible public, people think they know the real reasons for the war. A war of revenge? Come on, it is not an eye for an eye. Their is a bigger strategy, both geo-political and economic, for the war(s). It is myopic to think otherwise.
Islam plays a significant part of the WOT, being that the terrorist use the religion as their credo for the practice of terrorism. Unfortunately, most Westerners' equate Islam with terrorism. Islam is a peaceful religion with open ended doctrine, which allows the extremist to twist the words in their favor and exploit its founding of uneducated participants. Islam as a whole is not the entity the West is fighting. Terrorism, supported by Islamic-based people, are its targets.
To the question regarding the increase/decrease in terror, post 9-11. I find that this question is in itself limited by the fact that 9-11 occurred and again myopic. I am confident that 9-11 and the West's WOT has inspired more terrorism in the world. Yet, I do not believe it has exasperated a world movement of terrorism as many would like to purport, I.E. the Jihad v. McWorld school of thought.
Terrorism has been on a steady rise after the end of the Cold War. Both the fall of the USSR and its satellite states allowed for the once subdued terrorist movements to grow and spread radical ideologies without the friction of government intervention. We are currently seeing these ideologies in new venues of the world as they seek to control, either through religion or cultural idiosyncrasies, the once stable territories.
During the Cold War, these ideologies were quelled by dictatorships who promoted strict oppression of the terrorist view points; this was seen as detracting from the single governance view point. At present, no one is around but the U.S. to instill control and single uniformity. The terrorist organizations have more incentive to fight for their belief as they see the West as being the antithesis of their value system. Independent of 9-11, the problem is that little governmental resistance in the lands inhabited by terrorist organizations promote terrorism.
It is the truth that the West does group people of Islam together as being terrorists. We do so only to aid in identifying our enemy. Without such a identification we would be killing indiscriminately, like the Mongals. The association of Islam and terror is sad, but their is no existing alternative to this. Can you think of one?