The war in Iraq led to the collapse of al Qaeda support in the Persian Gulf. Al Qaeda declared the "battle for Iraq" to be a really big deal, and a struggle that they could not afford to lose. Al Qaeda did lose, and did so by killing over 50,000 Moslems and triggering an uprising by Islamic radicals in neighboring countries. Al Qaeda members in Saudi Arabia, who had long kept quiet inside the kingdom, in return for an informal truce and sanctuary, attacked. But once the bombs began going off in Saudi Arabia, popular opinion turned against the Islamic terrorists, and within three years, al Qaeda was crushed in what was, for all practical purposes, in its homeland. Many wealthy Saudis, who had long contributed large amounts of cash to Islamic extremists, cut their support. While al Qaeda lost most spectacularly in Iraq, they suffered even more damage because of their defeat in Saudi Arabia.
But then, you never really thought it was a good idea to take lectures from the anti-war side on military matters, did you?