Homeland Security efforts are ably reinforced by Homeland Defense and Defense Support of Civil Authorities (DSCA), which are missions executed by the Department of Defense (DOD), most specifically by the Combatant Command, United States Northern Command (USNORTHCOM). In supporting the nation when requested by DHS, FEMA, or other lead federal agencies, or as directed by the president or the secretary of defense, DOD provides many unique capabilities for crisis response. One specific function used most notably during the post-Hurricane Katrina period was the use of airborne assets to provide damage assessments and to gauge the extent of the sea surge at various times during the recovery. The function of deploying such assets is traditionally called (ISR). Yet the U.S. military cannot legally collect intelligence on U.S. citizens. Consequently, the action, as performed during the hurricane recovery operations described here, is known as (IAA). For some, the difference between these terms is merely semantics; for many, IAA differs both symbolically and practically from ISR, if not in how information is collected, then in how it is used and the motivation behind the collection. (The Web site for IAA reference is under Web sites references below.)