I honestly don't think that this will happen. Sending in the National Guard would make more sense in my opinion. Whatever they decide to do, they need to do it soon. The violence in Chicago is unthinkable, I can't imagine how scary it is to live there.
Not ok with a foreigner asking me for my ID and like Impaired, not ok with Americans asking for it either. I am not sure what can be done to stop the violence there but calling in the UN is not the answer.
I live in the Chicago area and I can speak first hand that the UN troops won't be needed because the National Guard and Reserves are close by.
My fiancee has lived here all her life and even though she knows there are gangs the police by themselves have handled it by themselves. I'm sure if they needed any outside reinforcements it will be faster then you think.