A Junior Military Officer (JMO) is typically someone who has spent 3-6 years active duty as a commissioned officer rank (O1 - O3). The sourcing for this can be Air Force, Army, Coast Guard, Marines or Navy. This is typically a very diverse group of candidates from various economic and social backgrounds. The commissioning sources for officers is Service Academies (West Point, Air Force Academy, Naval Academy), ROTC programs or Officer Basic Course.