The "Büro des Marinenachrichtendiensts" (Bureau of naval intelligence), short "BDM" or "Büro", is Rheinland's secret service and head of the Marinenachrichtendienst, tasked with Sirius-wide monitoring, gathering and processing of information, prevention of hostile acts, and neutralization of the alien menace in Rheinland. The BDM relies on a variety of measures, the majority of which are clandestine. If necessary, they even use ties to the criminal underground in order to accomplish their mission.

The BDM cooperates closely together with the Rheinland Imperial Police and Rheinland Military to maintain the national security of the House of Rheinland. Specialized personnel and the latest tools are required to ensure the agency's superiority towards its enemies. Members of the Büro are some of the best in Rheinland. They are experienced, capable and highly motivated to protect the fatherland. Beyond that, the Büro is also equipped with its own navy - The so called "U-Korps" - A small fleet dreaded for its guerrilla and economic-warfare tactics. Although their fleet size isn't as large as the Rheinwehr's, they are still able to adapt at any situation and can turn the outcome of a conflict in favor of Rheinland.