We didn’t immediately invade Iraq. The run up to war took a year and a half.
We’d been saber rattling since 1998. Saddam had been saber rattling even longer as he’d violated the peace agreement of the first Gulf War.
North Korea was also part of the Axis of Evil. They weren’t behind the 9-11 attack either.
Iraq WAS a state sponsor of foreign terrorism in Israel and elsewhere.
The run up to the Iraq war took 18 months and gave Saddam plenty of time to hide/export his WMD to Syria, et al. That fact is one of my quarrels with how W prosecuted the war - after the start Bremer also disbanded the Iraqi Army as well. Saddam was given too much time to hide the WMD.