This piece by John Lloyd in the New Statesman is worth a read.
The repeated invasions of contiguous states; the massacres of Kurds and southern Shia; the license given to torturers, rapists and murderers wearing the uniforms of secret police; the complete arbitrariness of Saddam's kleptocratic rule; the development of chemical and biological weapons and the attempt to develop a nuclear weapon - all of these made Iraq an internal hell and an external danger which, sooner or later, would have to be faced down. The glad hosannas of those who see in the apologies of some who backed invasion a vindication of their own opposition to it are simply signs of self-delusion. Worse, they are yet another evasion of the central question, which George W Bush and Tony Blair did have the nerve to face: what is to be done about dangerous tyrants, beyond hand-wringing, ineffectual and decaying sanctions and ever-more hollow-sounding resolutions at various international levels?