The Bulgarian Armed Forces are headquartered in Sofia, where most of the Defence staff is based. Until recently the supreme military institution was the General Staff and the most senior military officer was known as the Chief of the General Staff. After the latest military reform has been implemented the General Staff became a department within the Ministry of Defence and for that matter its name had to be changed to match the new situation. For that reason the former GS became the Defence Staff and the supreme military commander became the Chief of Defence. Currently headed by Chief of Defence general Simeon Simeonov, the Defence Staff is responsible for operational command of the Bulgarian Army and its three major branches. Deputies: Vice Admiral Petar Petrov, General Atanas Zaprianov, General Dimitar Zekhtinov.