Why do I keep seeing the claim that the Iraq war was completely unjustified?

last time I checked he was playing cat and mouse with us since the first Bush left office... we had a president who did nothing for 8 years as Hussein kept playing games with inspectors and continually raising suspicion as to what he was planning. Playing games with his military in the DMZ. All of which should have provoked some action yet it took another president to say enough games come clean or else.What is the unjustified part, if you keep bluffing someone has to call it.