The Communication and Information Systems Groups (Gp CIS), known until 2002 as the Transmission Troops or TTr (Dutch; Flemish: Transmissietroepen, French: Troupes de Transmissions), are the military communications units of the Land Component of the Belgian Armed Forces. They operate and maintain secure communications and information systems at strategic, operational and tactical level.
Each brigade headquarters was also supported by its own HQ company that included a Transmission platoon. In 2002, the brigade headquarters Transmission platoons were disbanded, and the independent Transmission units transformed into Groups CIS (Gp CIS). To support the brigades and subordinate units, five Groups CIS were established:
With the Transformation Plan of the Belgian Army and establishment of the Medium Brigade, the 2nd Group CIS and 5th Group CIS were disbanded in 2011, and its personnel was transferred to either the 6th Group CIS or the 4th Group CIS.
On November 22, 2018, the Medium Brigade was restructured into the Motorized Brigade that included both the 4th Group CIS and 10th Group CIS. The 6th Group CIS was integrated into the Special Operations Regiment (SOR).