Fleet Intelligence is just one part of a two headed beast that is responsible for all things related to covert recon and intelligence gathering. The SIC is the other half of this duo, and is responsible for civilian and Society related operations, whereas Fleet Intelligence is focused on all things military and Earthfleet related. However, due to the fact that they are, in essence, the same organization with two different titles, it's not unusual for their missions to overlap and key personnel from one branch of the organization quite regularly being re-purposed or reassigned to undertake missions for the other. So, on paper, the missions of each half of the organization is clear and defined, with no room for deviation. In practice, the lines between the two are heavily blurred, if sometimes completely non-existent.