"...it would be safe to say that the al Qaeda in Iraq affiliate, Jabhat al-Nusra, exists because of the Iraq invasion, and likely would find new authority & power if the US made Syria the next front "

"... One of Diehl's most fantastic assertions is the claim that the United States "faced down al-Qaeda and eventually dealt it a decisive defeat." Look, I was on the team after 9/11 that analyzed whether there was a relationship between Iraq and al Qaeda, and I was the chief targeting officer charged with following Abu Musab al-Zarqawi. The war in Iraq provided al Qaeda with a new front for its struggle with the West. After the invasion, Zarqawi -- the man who would lead al Qaeda in Iraq -- pledged allegiance to Osama bin Laden and, consequently, money and weapons flowed into the country. The United States didn't "face down" al Qaeda in Iraq; it inadvertently helped Zarqawi evolve from a lone extremist with a loose network to a charismatic leader of al Qaeda. By extension, it would be safe to say that the al Qaeda in Iraq affiliate, Jabhat al-Nusra, exists because of the Iraq invasion, and likely would find new authority and power if the United States made Syria the next front for the global jihadist movement.

Finally, Diehl misinterprets the outcome of the Iraq War by arguing that "U.S. influence in the Middle East remained strong." A year after the Iraq War, Pew conducted a survey that revealed the "vast majorities in predominantly Muslim countries continue to hold unfavorable opinions of the U.S." Our influence has been further undercut by the fact that we are broke and our political system is dysfunctional. The U.S. government is currently operating under sequestration, struggling to fund some of the basic needs for places like Syria. It could still employ superior military power in Syria, but 10 years of war have taken a toll on its troops and materiel. (Besides which, a more bellicose North Korea might soon demand more of its attention.) And the Iraq War also left the American people wary of military engagements -- and they are the ones who will pay the bills in money and in lives.

The argument that unleashing the U.S. military industrial complex can bring about desired results during a conflict should have been deflated, beaten, and buried by now. The winner of the Iraq War was humility, and it is a prerequisite for a wiser foreign policy. That's the only lesson that matters."