Here are more.
http://www.youtube.com/watch?v=bUqqlMuvpV0&feature=related
http://www.youtube.com/watch?v=-taU9d26wT4
One group of soldiers refused to violate the Constitution and follow an illegal order. No cops refused that I can find.
Katrina was an actual disaster with all that goes along with it. (rioting, looting, thievery, assults) There were criminal gangs running the street with weapons.
In that case, law enforcement had no choice.
I don’t think you can compare that to what the UN want’s to do. The scale of operation is totally different.
You have a city, half or more empty and a surrounding rural area vs the entire USA.
BTW: I’m not going to say that the Katrina operation wasn’t a dress rehersal for future events. It sure could of been.