Non-military foreign aid from the United States to other countries is the responsibility of the Agency for International Development. Now an independent agency, it has been a branch of the State Department, and also has gone under a number of other organizational names.
When the United States is involved with helping a Host Nation deal with insurgency, the U.S. military's foreign internal defense doctrine may route non-military economic development and humanitarian assistance through AID. AID, in turn, may need military resources to deliver supplies to areas lacking adequate transportation access or security.
AID is structured on geographic and functional lines, as well as having the usual range of administrative support offices typical of a large government agency. In each country receiving aid, there will be a local office, typically at least partially in the U.S. Embassy. In principle, the U.S. Ambassador heads the "country team", including diplomats, AID staff, military advisors and operational units, Central Intelligence Agency, and official government information (US-acknowledged press and public information) from the United States Information Agency. Given the personalities in each country team, the agencies may be more or less autonomous.
The geographic bureaus roughly correspond, in area of interest, to the military's Unified Combatant Commands that are organized geographically rather than functionally (e.g., United States Pacific Command (responsible for Asia and the Pacific) vs. United States Special Operations Command)
USAID's functional bureaus, which tend to work extensively with third countries and nongovermental organizations (NGO) are: