What are some instances of US intervention being detrimental to either the US or a foreign nation?

(school project) I have to support the idea that the US would be better off if it did not concern itself in global affairs; this includes foreign trade, assisting growing nations, and getting involved with international unions. My main topic is Darfur, I have to argue that we should not intervene at all. I think the best way to do this is to bring up historical instances when US intervention just made things worse.
If you have any ideas or can help me find information that will lead me on the right track that'd be great. These historical instances can be wars where we both failed to achieve or goals and we ended up making it worse for either us, by creating more enemies for ourselves, or the other nation, by leaving them in a much worse state then when we came in. There is also times when, as the US attempted to give aid to a nation we ended up with more violence. Thanks for any information or ideas you can give.

Haha, thanks you guys, I'll pick a best later. Yeah, he's not a "left wing wacko" That's just the veiw that I've been assigned to argue. (Though he is pretty liberal... :P )

Try your involement in the "Korean Conflict" aka WAR. And then look into Vietnam the ultimate fiasco or Cuba.
I'm sorry but the US warmonger's have put you in the position of the world's bully. When the US don't like something they feel they have "God given right" to fix things wether they need or want fixing at all. Look up the "Monroe Doctrine" and "Transvest Destiny" and the attitude is still shining strong.
Neighbour but no fan.

OK, I am assuming some left wing wacko teacher gave you this assignment.

While not everything we have ever done globally has worked, we have gotten things right, much more often, than we got them wrong.

Some examples of things that didn't turn out perfectly are:

1) Our support for Saddam Hussein in the Iran - Iraq war. Until he invaded Kuwait we consider Hussein a friend in that region.

2) Our support of Manuel Noriega. He turned out to be just another two bit petty tyrant, that we cut off and arrested after he got to big for his britches.

3) Our support of Usama Bin Laden and Mujahideen. We supported them in their fight to fight the Russians in Afghanistan.

Again until Saddam invaded Kuwait, UBL was a friend to the U.S. UBL turned against the west when he asked the Saudi Royal family to let him kick Saddam out of Kuwait and the Royal family accepted the coalitions offer over his. He took personal offense and started his own little war with the west.

all the above instances hav been detrimental..get a grip warmongers