Analysts assessing the potential threat posed by North Korea have long focused upon the Hermit Kingdom's vast army. However, recent trial launches of short-range ballistic missiles (SRBM) from a submarine have redirected attention to the 800-plus-strong fleet of Pyongyang's Korean People's Armed Forces Navy (KPAFN), which operates from a network of bases along the country's east and west coasts.
The activities of the KPAFN receive little publicity, although Pyongyang occasionally releases propaganda footage of its warships carrying out exercises.
The indigenous, nuclear warhead-capable KN-23 SRBM, which has an estimated range of 600 kilometres, is launched from a single silo in the conning tower of the KPAFN's Gorae-class diesel-electric submarine.
The Gorae submarines are based upon the old Soviet Golf-class, of which North Korea acquired a number for examination and subsequent scrapping. A further five examples are reportedly to be constructed, with one already being in build. Probably displacing about 2,000 tonnes, the 70-metre submarine has a top underwater speed of 10 knots and an estimated range of 1,500 nautical miles.
Although shunned by many in the international community, the Democratic People's Republic of Korea maintains defence relations with China, Iran, and, to a lesser extent, Russia, and its domestic defence industry produces warships and naval weapons, often developed from Chinese-built equipment.
The KPAFN currently operates some 80 submarines. There are about 45 examples of various versions of the 370-tonne, 32-metre Sang-O-class, a type which is active in hostile incursions into South Korean waters, while there are at least five of the small Yono-class.
Up to 30 of the old Type 033 submarines, which were supplied in kit form by China, remain on inventory.
Largest KPAFN surface combatants are a pair of 1,600-tonne, 1970s-vintage Najin-class frigates. At least one of them has been modified and fitted with new radars, two automated 30-millimetre remotely fired cannon, as well as Russian Styx anti-shipping cruise missiles (ASCM) that were removed from decommissioned fast attack craft (FAC).
The most modern surface warships are the pair of Nampo-class frigates. Very little has been seen of these ships, which were commissioned between 2013 and 2014 and are, like the Najin class, indigenously built. They reportedly displace around 1,500 tonnes and boast armament believed to consist of a 76-millimetre gun, Kamsung ASCMs, and Igla air defence missiles.
North Korea, furthermore, has for some years reportedly been working to convert an unfinished ex-Russian Navy Krivak-class frigate into an operational warship.
Also still operational, but of little military value, are four old 650-tonne Soviet-designed corvettes of the Sariwon-class.
There are more than 300 FACs on strength. Most modern are the six high-speed catamarans of the Nongo-class. These 200-tonne craft are reputedly capable of 48 knots, and the latest variants are armed with KF-35 ASCMs and a 76-millimetre gun.
A plethora of older vessels consists of a range of mainly Russian and Chinese-designed gun, missile, and torpedo equipped FACs, including Styx-armed Komar and Osa-type boats. Some craft are fitted with an 85-millimetre gun mounted in a tank turret, while others mount launchers for multiple unguided rockets.
There are also a number of small minesweeping craft, as well as many landing craft of various types and sizes, while the KPAFN operates a very big fleet of small assault hovercraft, semi-submersibles and fast, low radar cross-section craft dedicated to inserting teams of saboteurs and assassins into South Korean waters.
The recent SRBM missile firings entail a long-range role, with strong political overtones, for the KPAFN, but the service has no pretentions of being a blue water force. Najin frigates sometimes deploy further offshore in support of missile firings, but the service operates mainly within 50 kilometres of North Korea's coastline and is tasked primarily with countering attacks from the sea.
In accordance with the requirements of this role, the KPAFN carries out regular mass set-piece exercises but otherwise does relatively little time at sea. Many of its smaller warships are inactive for long periods, although a lot of in-harbour crew training is conducted. Intelligence reports indicate that exercises are carried out efficiently, although the relevance of such evolutions to modern sea warfare is debatable.
The other major commitment is to enable armed incursions into South Korea, with the aim of destabilising its neighbour and hampering the economic development of its border regions.
A large number of incurring North Korean hovercraft and fast boats have been destroyed over the years by South Korean forces, many by Sea Skua and Scorpion low-flying missiles fired from Lynx and Wildcat naval helicopters.
A Sang-o submarine grounded and was seized on the South Korean coast in September 1996, while a major confrontation between flotillas of North and South Korean patrol boats in June 2002 saw both sides sustain damage, deaths, and injuries.
An unidentified KPAFN submarine torpedoed and sank the South Korean corvette ROKS Cheonan in the Yellow Sea, in March 2010, resulting in the loss of 46 crew members.
