It's a matter of perception: will the UN be perceived as having a different agenda from the US or helping the US in reshaping Iraq?
The latter will definitely expose the UN to terrorist attacks.
But if the UN gave orders to the US rather than the other way around and the UN behaved much better towards the population, then there's hope.

I've just read an article about the Moon hoax conspiracies and their origin.
First, it's particularly fitting that Fox TV had to program that show, then it appears to be an american tendency, as well as UFO abductions, fear of the FBI, CIA, the UN, Satan and Communism, etc..
Those fears keep feeding the delirium of extremist groups.
All those conspiracy theories (invasion of the US by communists or UN blue helmets or whatever) show nothing more than excessive mistrust towards a government. But then, we live in democracies, don't we? We can always change the government, can't we? Communism is no more threat to the US than asteroid Eros is.

Raoul