The North Sea Fleet (NSF; ), concurrently the Northern Theater Command Navy, is one of the three fleets of China's People's Liberation Army Navy. Headquartered in Qingdao, Shandong, the fleet provides naval forces to the Northern Theater Command. In September 1950, the Qingdao Army Base was redesignated as a naval base. Following the departure of the Soviet Navy from Lüshunkou (Port Arthur), the North Sea Fleet was established in 1960 with naval bases in Qingdao and Lüshunkou. The fleet currently includes China's first aircraft carrier, Liaoning, as well as nuclear-powered attack and missile submarines. The North Sea Fleet was historically the most capable of the Navy's three fleets, being the first in China to operate destroyers, shore-based missiles and nuclear submarines. In recent years however, the shift in strengthening of importance and strategic capabilities of the East and South Sea Fleets are more prioritised.