I know it's wikipedia, but something to start from.

The United States Army Intelligence Support Activity (USAISA), frequently shortened to Intelligence Support Activity or Mission Support Activity, and nicknamed The Activity, the Army of "Northern Virginia,[1] or Office of Military Support, is a United States Army Special Operations unit originally subordinated to the US Army Intelligence and Security Command (INSCOM) but now part of the Joint Special Operations Command. It is tasked to collect actionable intelligence in advance of missions by other US special operations forces, especially 1st SFOD-D and DEVGRU in counter-terrorist operations."

https://en.wikipedia.org/wiki/Intelligence_Support_Activity