American forces have reportedly been operating in a gray area between assistance and direct action in Iraq

On Tuesday, Secretary of Defense Ash Carter announced that the US "won't hold back from supporting capable partners in opportunistic attacks against ISIL, or conducting such missions directly, whether by strikes from the air or direct action on the ground."

In a column for Bloomberg View, Eli Lake and Josh Rogin claim that last week's raid on a building near Hawija, Iraq where ISIS prisoners were being held was not "a unique circumstance," as the Pentagon puts it, but rather the latest in a line of missions supported by "extensive [special operations] infrastructure."

Lake and Rogin cite unnamed US and Kurdish officials, claiming that the US bases its operations out of a center in Erbil, in northern Iraq.

Those sources also said that the US has a special ops force called the Joint Terminal Attack Controllers supporting operations in the area and a group from the Marine Special Operations Command that trains Kurdish forces to fight ISIS.

Senator Bob Corker (R-Tennessee), who chairs the Senate Foreign Relations Committee, told the Bloomberg columnists that even congressmen weren't well-informed of the strategy. "I don't think Congress is always even close to fully knowledgeable as to what is happening."

While the Pentagon's press secretary said that he "would not suggest that [actions like last week's hostage-rescue raid are] something that's going to now happen on a regular basis," Carter refers to conducting more raids among the three changes that he's pursuing - along with tackling Raqqa, ISIS' Syrian stronghold, and retaking Ramadi, Iraq.