Our military enhanced its reputation by fighting and winning a drawn-out war in Iraq. Many enemies and potential enemies comforted themselves by claiming our victories in 1991, 2001, and 2003 were quick victories only made possible by our technology, but that we did not have the stomach for a long war.
Krauthammer writes, as I've long argued, that victory in Iraq is an opportunity to turn victory in Iraq into a much larger gain in the Middle East:
Second is the regional effect of the new political entity on display in Baghdad -- a flawed yet functioning democratic polity with unprecedented free speech, free elections and freely competing parliamentary factions. For this to happen in the most important Arab country besides Egypt can, over time (over generational time, the time scale of the war on terror), alter the evolution of Arab society. It constitutes our best hope for the kind of fundamental political-cultural change in the Arab sphere that alone will bring about the defeat of Islamic extremism. After all, newly sovereign Iraq is today more engaged in the fight against Arab radicalism than any country on earth, save the United States -- with which, mirabile dictu, it has now thrown in its lot.
Iraq became the central front in the war on al Qaeda because al Qaeda decided to invade liberated Iraq and make their stand in Mesopotamia. They lost. And now al Qaeda has retreated to their Pakistan sanctuary, possibly aiming to make nuclear-armed Pakistan their primary target.
A sovereign Iraq should offer to send troops to Afghansitan. That would be quite the symbol of our success in Iraq. And one that would make it easier to look back and label the day we won the war.