The North Korean Najin-class frigates are some of the largest vessels in the Korean People's Navy. Although they bear a striking resemblance to ex-Soviet Kola class frigates, they are unrelated to any Russian or Chinese design. The class was originally fitted with a trainable triple 21 inch torpedo launcher, which was replaced in the mid-1980s with fixed Styx missile launchers taken from Osa class missile boats. The design is inherently dangerous, and even a minor missile failure would result in significant damage to the ship.
At least one Najin-class ship appears to upgraded with much more modern weaponry in 2014. At Nampho the outdated anti-ship missiles, aft 57mm dual cannon, Drum Tilt fire-control radar and surface search radar were removed, and several new systems were installed. Most clearly identifiable are two 30mm automated turrets at the aft, likely based on the Soviet AK-630 CIWS, and two Kh-35 missile racks with the capacity for some 8 missiles in place of the older Styx/HY-2 launchers. The modernization program appears to be continuing as of December 2014.