The siege of Fallujah began with an expectation of weeks, if not months, of heavy fighting and worries about how that would influence Iraqis' willingness to cooperate with the interim government.
A week later, the US military has wrested control of a city that had become a stronghold of Iraq's insurgency and a stumbling block to elections slated for January.
But the value of the military success is already being sharply tested. Fallujah is occupied but not subdued, and the US faces a daunting task in repairing damage done from bombing insurgents' tunnels and blowing up weapons caches. Violence is also erupting in other cities across Sunni-dominated Anbar Province as well as in ethnically mixed Mosul, a major northern city.
Even as US forces move to consolidate their gains in Fallujah, say analysts, the real benchmark for progress will be political. If the Fallujah campaign isn't followed up by large numbers of Sunni leaders coming in from the cold and participating in Iraq's transitional arrangements, particularly elections, more violence is likely.
Now, "the interim government needs to be seizing the political initiative [and] stirring the hearts of the large Iraqi population that's sitting on the fence toward lending their support,'' says Mario Mancuso, a retired Special Forces captain who spent a year in Iraq and is back in the US in private legal practice. "It's important to recognize that military force is just one arrow in the quiver."
The challenge is to forge a political alliance that will see insurgents isolated from the civilian populations who have supported them and draw the country's powerful Sunni minority into arrangements for Iraq's political transition that they have viewed with suspicion until now.
Steps need to be taken to assuage Sunni fears and "get some buy-in from the nationalist Sunni middle into the idea of the new Iraq,'' says Mr. Mancuso.
Trouble in Mosul - a city of 1 million once so at peace that its management by the 101st Airborne Division was seen as a model for undercutting violence with targeted good works - could pose a particular problem for the US and Prime Minister Iyad Allawi.
The violence there - which has involved car bombs, looting, insurgent attacks on police stations, and the deaths of at least six Iraqi soldiers - is a reminder that today's successes come against a benchmark of deepening insurgency and lawlessness across Iraq over the past year.
"Mosul is warming up - people I talk to say that the next explosion is going to be there and that will make Fallujah look like a Sunday School picnic,'' says Whitley Bruner, a former CIA field officer who spent 25 years in the Middle East and now directs government relations for Diligence, a security and analysis firm in Washington.
Mr. Bruner says that while the focus has been on Sunni insurgents in Iraq's center, the chances of ethnic and sectarian problems remain high in other communities. "Mosul is teeming with people ... and there are seething hatreds between the Sunnis, Kurds, (and) Turkmen, including Shia Turkmen. It's a mess."
Going forward, he says, difficult political compromises are going to have to be made in the interests of stability. In particular, the US and the secular Shiite Allawi must build guarantees into the electoral process that will eventually lead to a new Iraqi constitution that protects against a potential tyranny of the Shiite majority.
"The Sunnis, but the Kurds as well - they are extremely restive now - are afraid that we are giving the country away to the pro-Iranians [and] there will be an Islamic republic, and they will be oppressed,'' says Bruner. "We have to make an Iraq that has guarantees for significant minorities and insignificant ones, too. We're not doing that, just alienating people."
As things stand now, Bruner expects a large number of Sunnis - who make up about 20 percent of the population but were favored under Saddam Hussein and have ruled Iraq for almost its entire history - won't participate in elections. If that happens, "you will get a Kurdish/Shia split in elections which will guarantee civil war... we have got to do something to make it clear the Sunnis have a role to play."
Mancuso agrees that reassuring Sunnis is the goal now, though he's less worried about civil war. He says the political strategy should be to split the broad mass of Sunni nationalists from the hard-core minority of Sunni Islamists who are less likely to compromise and many of whom seem bent on martyrdom. "This [political] battle will take months, but it starts in earnest now. It will only be successful if a large portion of [Sunnis] can see that a future democratic Iraq includes a political structure that is amenable to them,'' he says.
Iraq's Shiites have long been an oppressed majority, and seem determined to wield their latent political power. Grand Ayatollah Ali al-Sistani, Iraq's most respected cleric, has urged Shiites to vote. Though most appear to oppose an Islamic government along the lines of Shiite Iran's, many Sunnis fear that is what will happen.
For the moment, the US strategy seems to be to keep rolling over any clusters of insurgents that it can find. Rather than wait and see if demonstrated US battlefield superiority in Fallujah will induce insurgents to negotiate a way back into the political process, US war planners appear to have decided that pausing will simply allow their opponents to regroup.
Army Gen. John Abizaid, head of US Central Command, indicated that US forces will be tough with Iraqis who align themselves with insurgents.
"The coalition and the Iraqi government will not tolerate temporary alliances of convenience," he said, as quoted by the American Forces Press Service. "Once you [do that], you've crossed the line and go on the list. [T]he only way off is to be killed or captured."
Louis Cantori, a retired marine and professor at the University of Maryland, says Mosul emphasizes a running problem - not enough US troops to control the situation.
"Note the assignment of the Stryker Brigade north to Mosul to quell the revolt there when the cordon around Fallujah still needed to be maintained," he says.
• Faye Bowers contributed to this report from Washington.