Najin-class Frigate, 631 (2014)

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Najin-class Frigate, 631 (2014)


North Korea’s first major indigenous ship, and still the largest produced to this day. Armed with 8x Kŭmsŏng-3 (Kh-35) AShMs, 2x 100mm cannons, 1x dual 57mm cannon, 2x 30mm auto-cannons and 6x 25mm auto-cannons.

The Korean People’s Navy (the KPN, or KPANF) was founded in 1946, and with the onset of the Korean War, was provided with a number of small torpedo boats by the USSR (and later China) that formed the bulk of its equipment. By the end of the Korean War in 1953, the DPRK’s navy was in dire need of new equipment. Throughout the 50s and 60s, the DPRK was armed with torpedo boats, gunboats and submarine chasers from both the USRR and China. The DPRK modified a number of these ships, and built their own slightly modified versions to better suit their needs.

In the early 70s, the DPRK began its construction of its first indigenous ship ‘of true importance’. These were named the Najin-class by the US DoD, after the shipyard where they were built (라진, also less commonly romanised as ‘Rajin’). Two ships were built, initially numbered 3025 and 3026. These numbers were quickly changed to 531 and 631. No. 3025 (531) entered service in the East Sea in 1973, and No. 3026 (631) entered service in the West Sea in 1975. The ships were almost immediately out-of-date for their time. A few upgrades have occurred since – in the 80s, both ships had their torpedoes removed and replaced with AShMs. At some point in the 80s-90s, the ships received different machine guns. In 2014, No. 631 was modernised with new missiles and other weaponry.

This suggestion focuses on No. 631 in its 2014 configuration.

While the Najin-class are indigenous ships, they have noticeable design similarities to the Soviet Kola-class (Project 42) frigates, built in the 1950s. While the Kola-class are 96m long, the Najin-class are 103m long. Specifications such as armour and weight are unknown, but can quite reasonably be estimated from the Kola-class ships and all the available information.

In the 80s, 2x P-15 ‘Styx’ AShMs, were mounted to replace the triple torpedo launcher. The 2014 upgrade sees these replaced with Kŭmsŏng-3 missiles. These are a domestic variant of the Soviet/Russian Kh-35. They appear to have a few design changes over the Kh-35, possibly improving it to the level of the Kh-35U. The missiles have a range of 130-250km and a payload of 145kg HE. These will obviously need quite big changes to naval before they can be added, if added at all. Two quadruple missile racks are present, giving the ship 8 missiles total.

One 100mm/56 B-34 naval gun is located at each end of the ship, the same as on a number of Soviet ships in game. Directly behind the front 100mm cannon is a dual 57mm/70 ZiF-31 cannon. This is a Soviet naval gun designed in the 50s – they were clip-fed, and could fire at 50 rounds/minute.

In place of the aft 57mm as was present on the older variants are 2x AK-230 30mm turrets, side by side. Where the aft AK-230 used to be in the 90s, there is now a MANPADs-based SAM launcher, as well as 6x 82mm chaff/smoke launchers next to it. There are also 6x 25mm 2M-3s located around the front of the ship.

Strangely, the 533mm torpedo launchers are back, having originally been removed in the 80s. There are now 2 launchers fitted on either side of the aft 100mm turret, likely the Soviet Type 53 (possibly the 53-38).

In this configuration, the ship likely has a “Drum Tilt” (MR-104 Rys), “Skin Head” (Zarnitsa), “Pot Head” (Reya), “Pot Drum” and “Slim Net” radar.

The ship is said to either have 2 diesel engines, produced 15,000bhp (Jane’s, post-1995), or 3 engines, producing 18,000bhp (Guide to Combat Fleets of the World, 2001). The ships have a speed of roughly 26 knots (48km/h).

The Najin-class in its 2014 configuration would likely be a high/top-rank frigate for a future coastal tree for North Korea, as either a sub-tree for China’s future fleet, or as part of a United Korean tree. I will reserve giving a BR suggestion, as I don’t know how AShMs would affect its BR – matchmaking would need to be altered to allow for more missile ships to enter the game. If added without AShM functionality, the 2014 configuration has better AA capability than both the original 1973 configuration and the 1993 configuration, due to the addition of the SAMs, and so would be the best variant either way.


  • General
    Displacement: Unknown, > 1600 tons
    Engine: 2x Diesel Engines, 15,000hp
    Top Speed: 26 knots (48km/h)
    Crew: ~180

  • Armament:
    Main Armament
    2x 100mm B-34
    1x dual 57mm ZiF-31

    AA Armament
    2x 30mm AK-230
    6x 25mm 2M-3
    Unknown SAM launcher (MANPADs)

    Torpedo Armament
    2x 533mm torpedo tubes

    Missile Armament
    8x Kŭmsŏng-3 AShMs (Kh-35 derivative)

  • Sensors and Systems:
    82mm Chaff/Smoke launcher
    "Skin Head” (Zarnitsa) Radar
    “Pot Head” (Reya) Radar
    “Pot Drum” Radar
    "Slim Net” Radar

Few images exist of the modernised ship. Below are the only images I’ve found (I’d be very grateful if someone else had more)

  • Satellite image (Google Maps) of the ship undergoing modernisation in 2014. Some changes are visible, like the 2x 30mm guns at the rear and the removal of the aft 57mm

  • Kim Jong-Un inspecting the missile rack


  • One of the few photos of 631 in any configuration, back in the 90s



The Armed Forces of North Korea: On the Path of Songun – Stijn Mitzer and Joost Oliemans

KPA Navy flag ship undergoing radical modernization | NK News

North Korean Kh-35 Anti-Ship Missiles Shed Light On A Modernising Navy - Oryx

Kumsong-3 (KN-19) | Missile Threat

패션.역사.군사의 아침안개 블로그 : 네이버 블로그

The Unknown Warships of the Hermit Kingdom! – The Searchers

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Who knew the DPRK had a naval industry? Cool! +1