In keeping with the emphasis on strategic forces, the Navy's submarine fleet is being modernized by the acquisition of several classes of strategic and tactical submmarines. Up to 10 Borei/Dolgorukiy-class SSBNs are planned to replace older classes in both the Northern and Pacific fleets. These are being complemented by new Yasen and Khabarovsk-class SSGNs, as well as conventional submarines of the Improved Kilo and Lada classes. However, in terms of the tactical nuclear submarine fleet, it is unclear whether the new Yasen-class, Khabarovsk-class, and potential follow-on models, can be produced in sufficient numbers, and on a timely basis, to replace aging older model nuclear submarines on a one-for-one basis. It has been reported that Russian third-generation nuclear submarines have not been modernized to a level to avoid block obsolescence before 2030.