Why did US launch a war against Iraq?

Explanation

On 19 March 2003, the US launched a war against Iraq under the codename of Operation Iraqi Freedom. to be joined by forty other countries under the leadership of the US on the ground to prevent Iraq from developing weapons of Mass Destruction (WMD) without no evidence against Iraq. Hence, the ostensible purposes were different as controlling Iraqi oilfields and installing a regime friendly to the US.