According to officials I spoke to in Iraq last month, the hope is that a new group of volunteers from the region known as the Mosul Liberation Battalion will be the tip of the spear. Last month, Osama al-Nujaifi, an Iraqi vice president, told NBC News that the battalion had already conducted a number of raids inside Mosul against Islamic State occupiers.

But other Iraqi officials told me that the militia was largely untested, and it was unclear whether its leaders would have any credibility with the population inside the city.

A senior U.S. official who was briefed on the latest plans to take Mosul told me the new battalion was trying to surround the city and put it under siege. But he, too, said he did not know if the group was capable of helping administer Mosul once it fell.

So the situation is this: U.S. military leaders are openly talking about an imminent offensive on a city of more than a million residents who are widely distrustful of the Baghdad government; it’s unclear whether the projected front-line troops for the invasion are up to the task; there seems to be no comprehensive plan for what happens after the fighting stops. It’s enough to make one think the uncertainty over the time table isn’t the worst thing, if indeed a delay might help clarify some of these issues.