President Obama announced that he was sending an additional 200 troops to Iraq to add to the 275 troops that were sent in earlier and the 300 advisors. Although these people are called advisors, they are not accountants and lawyers and economists and academics in suits. They are usually Special Forces and other armed military personnel who could well end up in a shooting war. So the number of armed personnel sent back is now actually 775 and there is a real risk of some incident where they kill or otherwise injure Iraqi civilians.
One of the major sticking points that led to the US pulling out its combat forces from Iraq was that the Iraqi government was unwilling to grant immunity for the actions of US personnel in that country. Via Marcus Ranum, I learn that Iraq has quietly given the US “acceptable assurances” that these advisors would be shielded from local laws and this would likely extend to the 475 other troops as well.
The catch with these immunity deals is not usually about what these people do in their official capacity. As we have seen in other countries where US troops and other personnel have been stationed, it is when they get involved in some private dispute with the local population and the US uses their immunity status to let them escape any consequences. Recall the case of CIA operative Ray Davis in Pakistan. It is that kind of thing that causes great anger, similar to how people get angry when diplomats use their immunity to ignore local laws with impunity.