Grenzschutzgruppe 9 der Bundespolizei, also known as GSG 9 der Bundespolizei and GSG 9, is the elite tactical unit of the federal police force of Germany.
After the Bombing of the Vienna International Centre, the Joint Counter Terrorist Centre began a search for Bucky Barnes, who was believed to be the perpetrator. Discovering Barnes was residing in Bucharest, the JCTC tasked GSG 9 with apprehending him and shooting him on sight.
However, right after they broke into his apartment, Barnes and Captain America fought against the police officers and tried to escape. Suddenly, Black Panther showed up and tried to kill Barnes. Falcon helped Rogers to take down a GSG 9 helicopter and the pursuit continued in the city's tunnels.
Barnes was avoiding GSG 9 operatives while T'Challa ran after at full speed. Rogers took one of the GSG 9 cars and tried to keep up with them. As T'Challa stopped Barnes, War Machine arrived and helped GSG 9 apprehend Rogers, Barnes, Wilson and T'Challa.