As the Pentagon continues to add ground troops to Iraq for the ISIS war, it is expected that considerable numbers of private military contractors will follow.

Currently there are around 1,800 such contractors working for the State Department, and Secretary of Defense Chuck Hagel has ordered another 1,300 sent. This will likely be just a fraction of the overall deployment.

At the peak of the US occupation of Iraq, there were over 163,000 contractors involved in the war. The use of contractors allowed the US to mask the size of the overall deployment, but was controversial because of both cost and oversight problems.

The Pentagon made it clear, before they even started going into Iraq this next time, that they were looking for contractors for long-term deployments. Officials say the exact size will depend on how spread out the actual ground troops are, but signs are it will be considerable.