AlaskaBoy:

Putin did not extinguish whole populations of undesirable groups with weapons of mass distruction, nor use them in the Iran conflict, nor threaten to use said weapons against the United States.

There's your reason number 2.

The people of Chechnya and maybe Georgia might disagree with you.

Sadaam's actions in the Iraq-Iran war (when he was supported by the U.S.) were not offered as the justification for the invasion.