 Zvezdochka would carry out ship defectation, repair mechanical parts, replace nuclear fuel and all electrical equipment of the submarines.The submarines were also expected to receive a new sonar, combat information management system (BIUS), the GLONASS navigation system and new armament consisting of the Kalibr cruise missiles.In March 2015 it was reported that the final decision on the modernization of submarines "Carp" and "Kostroma" was yet to be made due to cost issues.