The work of the guards involved carrying out repair work on the defences, monitoring the zone from watchtowers and bunkers and patrolling the line several times a day. Border Reconnaissance (Grenzaufklärungszug or GAK) soldiers, an elite reconnaissance force, carried out patrols and intelligence-gathering on the western side of the fence. Western visitors to the border were routinely photographed by the GAKs, who also oversaw work detachments maintaining the fence.