When I joined DU in 2002 I learned about the PNAC (Project for the New American Century) neocon agenda, which existed before 9/11. They saw the collapse of the Soviet Union as an historic opportunity to use the unparalleled might of the US military to forcibly change regimes, starting with Iraq.
The problem was garnering support from the American public. They stated something like "a new Pearl Harbor" was necessary, then 9/11 provided it. The Bush/Cheney administration launched a systematic campaign of misinformation and lies to conflate Iraq with 9/11, and to convince the public Iraq had rebuilt their biochem and nuclear weapons program, which they hadn't.
Bush put the pressure on, and Iraq allowed UN inspectors into all their facilities to demonstrate there were no WMDs. The UN team was very close to declaring the extensive facilities necessary to enrich uranium and build nuclear weapons did not exist in Iraq.
The rationale for war would have evaporated along with the "mushroom clouds" over American cities Bush told us to fear. So they told the UN inspectors to evacuate before launching "Shock and Awe" in Iraq.
It was a war crime. Now we have another war crime in Iran, with the POtuS claiming there was an "imminent threat" of a nuclear-armed Iran. Another LIE.