WTF are you on about? Haiti isn't a war. It's a failed state. The US is funding an effort to prevent this turning into (more of) a humanitarian disaster by trying to get a reasonable police force in to enforce some kind of order.

Also, they're arguably preventing the possibility of armed conflict with neighboring Dominican Republic, a reasonably well functioning county that nutjobs in Haiti might try stealing from. (I spent a week there recently, nice place if you like beaches)

Personally I think it'd be fine (and a lot cheaper) to just help the Dominican Republic defend their border better and let Haiti collapse and the people starve. But I'm not into warm and fuzzy humanitarian missions...