Yes indeed. I thought it odd that the USMC was being sent in. Marines are not renowned for humanitarian operations. They are really good at engaging combatants, breaking stuff and killing enemy combatants. Actually, the best in the world.
The Marine definition of "self-defense" is a little broad. Someone shoots at them, they level entire blocks. Remember, under posse commitatus, they can't patrol to restore law and order, but they can defend themselves if attacked.
That, and they're amphibious troops by definition and equipment, so they're perfect for SAR in Lake Nagin.
Per WBRZ (Baton Rouge TV station)
Special FBI agents are in the Crescent City....