Humanitarian Assistance Operations are "programs conducted to relieve or reduce the results of natural or manmade disasters or other endemic conditions such as human pain, disease, hunger, or privation that might present a serious threat to life or that can result in great damage to or loss of property. Humanitarian assistance provided by US forces is limited in scope and duration. The assistance provided is designed to supplement or complement the efforts of the host nation civil authorities or agencies that may have the primary responsibility for providing humanitarian assistance" (JP 1-02).
What kinds of endemic conditions do the Human Assistance Operations entail? 
human pain, disease, hunger, or privation that might present a serious threat to life