After completing his military service as a Reserve Officer at the submarine base of Toulon, Danjean passed an examination to join the French DGSE as a civil servant. He carried out numerous missions in Sarajevo in 1995 and 1996, especially during the Siege of Sarajevo and the signature of the Dayton Agreement. He became a permanent member of the French Embassy in Sarajevo from June 1996 to September 1998.