He was later appointed as the commander of the Special Operations Forces at the Turkish General Staff Headquarters in Ankara.

In 1992 Koşaner was promoted to the rank of brigadier general and was appointed with the command of the Logistic Planning Department and later the 1st Commando Brigade of the Turkish Army.

Koşaner was promoted to the rank of major general in 1996 and was appointed with the command of the Turkish Army Academy.

Koşaner, along with the leaders of army, navy and air force simultaneously requested to relinquish their duties and asked for their "retirement" on 29 July 2011, just few days before the important meeting scheduled for 1 August 2011 to discuss appointments of senior military officers.

The New York Times stated that their action was to protest the "sweeping arrests of dozens of generals" as a part of a conspiracy investigation.