What do you mean by scope? Mission or geographical?
I suspect that initially its role is mostly symbolic - to demonstrate that the new Iraqi Army is more than just a constabulary subordinated to American power, but will when ready assume responsibility for Iraq's national defense. All those idiots from Turtle Bay to the Quai d'Orsay* clamoring for a date certain for withdrawal either don't know or don't care that Iraq's various unfriendly neighbors all have rather large armies. This is the first big step toward addressing that shortcoming.
BTW, the article has this sentence: "'They patrolled the local area around Taji both mounted and dismounted with the Calvary. They walked the local markets and interacted with the people,' Col. Styles said." I sure hope that the author, and not Col. Styles, said that. There is a world of difference between the Calvary and the cavalry.
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* That rhymes! I'm a poet and I didn't even know it. I should trademark that phrase (Turtle Bay is where the UN HQ in New York is located, and the Quai d'Orsay is where various French government offices are located. Comparable to "Foggy Bottom," it is common shorthand for the French Foreign Ministry).