I have no doubt that Iran is a supporter of terrorism. They provide aid of every sort to those who seek to destroy Isreal. But did they have anything to do with 9/11? I would say no. And the Bush administration has offered zero proof otherwise. To use the 9/11 atrocity as an excuse to wage war against Iran is not right. Especially when the evidence points to our so called "allies".
If Iran supports Islamic Jihad and Hizbullah , which are part of Al-Qaeda, and Al-Qaeda attacked us, Iran supported those who attacked us.
They still do so.
That is a reason for a regime change.