No, the greater concern is from the Iranian, Syrian, and Chechnyan militants. I know this as a fact. True, we could have secured the border first, and then fought through to the interior of the country, sounds pretty tactically inefficient if you ask me. I would state that the war plan, by Tommy Franks, was pure genius, even more so considering the fact that he had to adapt it at the last minute to deal with the fact that the Turks were not going to allow our 4th ID to come in from the north. However, that technicality always gets lost among the details.
In war, there are always going to be new ways that the enemy is going to try to continue to reinforce and resupply themselves, regardless of what kind of cordon you set up. There is always an underground in every war. However, most populations will tire of the ceaseless bombardment and eventually begin to give up those in the underground, in an effort to relax the stress of constant bombardment. That stress does not exist in Iraq right now, therefore, we have a dirth of intelligence coming from the streets. Basically, the people are more afraid of the outside militants than they are of US force, therefore, they remain quiet about what is actually happening.