Let me be clear... I was never in favor of a full-scale invasion of Iraq. That said, in 2003, the country was still extremely hot after a series of attacks culminated in 9/11. Whatever the reasoning, Saddam was perceived as a real danger, and the UN agreed on this in many aspects.
We knew he had the capability of producing nerve agents. He used them on his own countrymen, and on Iran. After his disastrous Kuwaiti "adventure", there was a perception that he was out for vengeance. A freighter in New York harbor that delivers a few tons of aerosolized VX or GB would potentially kill hundreds of thousands. And Saddam did NOTHING to dissuade the world that he did not have WMD. On the contrary, he cultivated the perception. He strutted and played to the notion that yes indeed, he had them. The decision was made to take him down.
These people were not running in fear for their lives... they were there to celebrate the toppling, and proceeded to spit and stamp on the many thousands of Saddam images in Iraq.
The majority of the people (non-baathists) were ecstatic.
Baathists, Saddam acolytes, and foreign fighters flooded the nation to fight the infiel, and the rest is history. A good read on the invasion itself:
In the company of Soldiers, by Pulitzer-prize winner Rick Atkinson.
Today, the U.S. is split on whether there was a Saddam / 9-11 connection. Most agree there was little to no connection... but that didn't make Saddam any less of a threat.
@Luftwaffe: Chemicals used in Vietnam were Agent Orange (a defoliant) and non-lethal tear agents to smoke VC out of tunnels. We had a huge stockpile of the real deal (organophosphate nerve agents like VX) but they were not used in Vietnam.
No one knew that agent orange would cause health issues. Our own troops operated in those areas after defoliation, and thousands became ill.
