What REAL reason did the United States have for invading Iraq?

I would love to know a logical reason for invading Iraq. I have never heard one. Sure we took down a tyrant buy I never saw the blueprints for the next tyrant that would feel our wrath lol. Technically we have made them more vulnerable for taliban takeover. I do think Cheney had some influence there, but honestly I don't think we'll know the truth for a long time.