In the US Navy, 171X is the designator for a Special Duty Officer qualified as a Foreign Area Officer (FAO).
The responsibilities of a FAO include:
Advising and assisting in planning and implementing policy related to politico-military aspects of international affairs
Providing background information on international developments of interest to the Navy
Interpreting and evaluating the politico-military significance of international developments
FAOs are grades O4 to O6. They advise on the politico-military aspects of international affairs.
Commissioned officers in the Navy must:
Have a degree from a four-year college or university
Complete Officer Training
Commissioning programs include:
NROTC
Naval Academy
Other undergraduate degree opportunities