Almost since Beechcraft started producing light twin turboprops, all the US services have been operating them as utility aircraft, trainers, and as intelligence/surveillance/reconnaissance platforms.
The latest variant to be fielded is the US Army’s MC-12S. Based on the Beechcraft Super King Air 350 ER, the planes are used to provide both full motion day/night video surveillance and a significant electronic intelligence collection capability in low threat airspaces. Due to funding and development issues, the actual mission equipment varies across the fleet. The end state desired is known as Enhanced Medium Altitude Reconnaissance and Surveillance System - Multi-Intelligence (EMARSS-M). Some of the airframes are modified MC-12W Liberty recon birds turned over from the US Air Force recently. The Air Force used their full motion video capability in support of Task Force ODIN, a counter IED operation. While they retain that capability in Army service, they can simultaneously conduct ELINT operations.
Another variant of the MC-12S carries a synthetic aperture radar with Moving Target Indicator capability known as the AN/ZPY-5 VADER, or Vehicle And Dismount Exploitation Radar. Basically, it’s a radar sensitive enough to track individuals on foot.
In March of 2016, a Beech Super King Air crashed in Iraq. Interestingly, it was in civilian markings, with a civilian registry. But it was also quite clearly modified for some sort of ISR role, and the registration clearly showed it belonged to the US Army. Exactly what it’s mission was is unknown.
Now, the MC-12S and its variants aren’t a secret. But nobody likes to go into too much detail of what they do, how they do it, and where and when they do it. But they will show off a little bit.