In 2004, the town of Fallujah was the scene of some of the most pitched fighting between US forces and Iraqi insurgents. It was credited as a turning point that helped solidify allied control of Anbar province and set the groundwork for a more stable Iraq.
News that the town has once again been taken by rebels aligned with al-Qaeda has people wondering if allied efforts there were for naught.
"The people who attacked us on 9/11 now own the key battleground in a war we launched ostensibly in response," writes James Joyner of Outside the Beltway blog. "Aside from regime change itself, it's not clear that we accomplished a single one of our objectives in that conflict. There was no nuclear program. The chemical weapons cache consisted of a few leftovers from the world wars. The Maliki government is corrupt and incompetent to provide basic security for the citizenry. And now al-Qaeda is running major outposts."
This wouldn't have happened if the US hadn't hastily pulled out of Iraq, writes Digital Journal's Abdul Kuddus: "With the withdrawal of US forces from Anbar province two years ago, al-Qaeda took advantage of the power vacuum and drove out the Iraqi forces."
It could be only a matter of time, he continues, before the whole of Anbar province is under control of al-Qaeda's Islamic State of Iraq and the Levant. "The group's success in controlling Fallujah could mark a shift in Iraq's sectarian violence from car bombs and suicide attacks to ground battles," he writes. "Images of al-Qaeda's black flags flying in Fallujah, where more than 1,300 US troops were killed during the war, only undermines the White House narrative of success in Iraq."
This could even be the beginning of an al-Qaeda state that encompasses northern Syria and Western Iraq, writes Max Boot in the Wall Street Journal. At the very least, he says, Iraq is heading toward a Syrian-style civil war.
"Prime Minister Nouri al-Maliki has no-one but himself to blame," he writes. "If he had embraced the Sunni Awakening movement, Iraq likely would have remained relatively peaceful. Instead, the moment that US troops left Iraq, he immediately began victimizing prominent Sunnis."
And what about US promises to help? "The US lost most of its leverage to do that when it foolishly pulled its troops out of Iraq at the end of 2011 after the failure of half-hearted negotiations overseen by Vice-President Joe Biden," he writes. The only choice for US officials now is to condition any military aide on Mr Maliki agreeing to be more supportive of Iraqi Sunnis.
(BBC Monitoring has an interesting collection of views on Mr Maliki's handling of the situation from the Iraqi press.)
The Nation's Greg Mitchell pins blame on the George W Bush administration for getting us into Iraq to begin with.
"One of three American lives lost in the ten-year war expired in 'pacifying' Anbar," he writes. "Then there are the tens of thousands of Iraqi lives lost in that province, and the utter devastation of Fallujah (and lingering health defects). What a tragedy, what a waste, even as war criminal Bush draws praise for his paintings of dogs and [former Vice-President Dick] Cheney earns applause on [the late-night talk show] Leno."
Fox News national security analyst KT McFarland writes that both Mr Bush (for getting the US into Iraq) and Mr Obama (for getting the US out too soon) are to blame.
"We failed to realize one essential truth of the Middle East - that the nations in that part of the world aren't just like us," she writes. "What seems clear now is the Iraq War wasn't over just because we said it ended when we left two years ago. The battle will continue, expand, and the entire region seems poised to suffer from a generation of civil war of epic proportions between Shiite and Sunni Arabs."
Not everyone is pessimistic about the current developments in Fallujah, however. Lt Col Robert Bateman writes in Esquire that the town, "half the size of Akron, Ohio," has little strategic significance.
"We thought that the place was important. It is not now, and, sadly, it was not then," he writes. "There are really only a couple of ways in and out of the city, which pretty much dooms the al-Qaeda idiots who 'took' the city on Saturday to a fairly rapid death. And we don't have to lift a finger this time. The Iraqis, the army and the paramilitary 'special police,' with select units, are going to Fallujah, and they are going to utterly crush the al-Qaeda elements there."
Even if Bateman's predictions come to pass, the optics (as they like to say here in Washington) of a black al-Qaeda flag flying in Fallujah aren't good.
Few remember that US forces eventually beat back the Viet Cong during the Vietnam War's Tet Offensive in 1968. It was the symbolism of the moment that was important. What the American public may take out of this story, as commentators from across the political spectrum try to assign blame and gain political advantage, is that Iraq is slowly sinking back into chaos.
(For the latest on the story, watch BBC World News America tonight, when Katty Kay will interview Seth Jones of the Rand Institute and David Gordon of the Eurasia Group, who identify the resurgence of al-Qaeda in Iraq as one of the top risks of the coming year.)