You must read this important article by Abraham Sofaer in the Wall Street Journal.
The London bombings generated revulsion and resolve. But unless states threatened by terrorism can be convinced to respond with deeds that in fact demonstrate resolve, the terrorists will grow stronger. It is time for the international community to accept that collective action in Iraq can no longer be regarded as illegal or illegitimate; that however marginal Iraq may have seemed to the war on terror in 2002, it is now central to that fight; and that true solidarity in Iraq would ensure an acceptable outcome, help restore the credibility of collective security, and discourage rather than reward terrorism.
He then explains why the effort in Iraq today is legitimate, and how solidarity in supporting that effort will work toward the defeat of the jihadists.
He concludes with, in part:
The notion that the war in Iraq has made the world less safe from terrorism is a baseless rationale for abandoning an essential objective. Every new act of terror can conveniently and fallaciously be used to prove the point, as though it would not have otherwise occurred. We are confronted today not with the consequences of what we have done in Afghanistan and Iraq, but with the consequences of having failed to end Saddam’s rule in 1991, and of having allowed al Qaeda to advance their aims for some eight years after they had made their intentions clear.