Some people in this thread are commenting on how terrorists appear to be stupid. Most people in the world are stupid in that they are not capable of creating a major attack on a superpower. Yet among all the stupid people there needs only to be one smart person to get the job done. For example, the American Revolution was created by some 100 men in Philidelphia to rid their colonies of the British, 100 people could not fight an empire, to fight an empire there must be many more people to achieve a critical mass to fight. It is very likely that there is at least one smart person that has the power to control terrorists. Thomas Jefferson is an example of a smart person in control of a country, same with Dick Cheny in the current USA.

I may not enjoy what the terrorists do, yet, I know that I have some respect--the same respect I have for the Bush Administration for running such a propaganda campaign to get the USA into Iraq--for a group of people (or person) that can mastermind such a sucsessful attack on the USA.

To respond to Superguy's idea of "I don't think America's imperialist, but I do think it's a bit too nosy. And that nosiness with even good intentions can and has gotten us into trouble."
The USA has done many "bad" things with good intentions such as torture. The USA has also done some "bad" things with "bad" intentions such as getting into Iraq for oil. Even with all the "bad" the USA has done I would not choose to live anywhere else in the world.

To respond to CessnaJock's idea of "The jihadists' intent is to kill Americans." I agree with Bart.
The whole point of terrorism is to incite terror within a group of people. I agree with your idea of "the jihadists' intent is to kill Americans" yet this is not the whole intent. The idea of the terrorists is to make people around the world fear them. In reality the 3,000 people that died in the 9/11 attacks are not that many people, the fear that the murder caused upon the other 300million people in the USA is the true goal.

If I assume my own definition of terrorism as correct an attack on airplanes will not be the most horrific possiblility of a terrorist attack. An attack on a school would be the most horrific. To provide an example I will use an unnamed school in Bellevue, Wa where I am familiar with the campus. The terrorist would drive into the school at 11:30 during a rainy winter day. The terrorist would wear a suicide bomber belt under his coat and claim he needs to give a lunch to his child. The terrorist would walk into the middle of the lunchroom and blow himself up, killing at least 200 children. All of this is possible with no security and minimal planning. It would not be very hard to plan this attack and repeat it in 100 schools at the same time. That attack would truly be the worst-case terrorist scenerio of all.