The M-1978 (KOKSAN) is a 170 mm self-propelled (SP) gun of North Korean design and manufacture. Very little information is available due to the secretive nature of the North Korean Government. What is known is that it is a 170 mm (~6.69") self-propelled gun of the open turret type. It was first seen publicly during a military parade in 1985.
While information on the M-1978/M1989 KOKSAN is poor it is probably mounted on a T-54 chassis, a Chinese Type 59 hull or a T-62 chassis. The 170 mm gun has no superstructure, and it has 2 large spades at the rear. The 170 mm gun itself is a previously unknown type, possibly Russian coastal-defence or ex-naval weapon. The Koksan is named after the city in North Korea where it was first seen by the West in 1978. The M-1978 version carried no on-board ammunition supply.
The M1989 KOKSAN is a later version or modified M1978 which carries 12 rounds on-board ammunition supply.
North Korea employs the M-1978 and the upgraded version the M1989 in batteries of 36 vehicles mostly along the Korean DMZ. They are usually hidden behind sand or earth covered, five meter tall concrete structures.
The only known combat deployment of the KOKSAN is during the Iran–Iraq War. North Korea supplied the Iranians with these guns who used the guns with good effect against well-reared Iraqi batteries and positions.