A shipyard in North Korea shifted production from semi-submersible boats to troop transport submarines early this year and produced at least seven of the new vessels by October to celebrate the 70th anniversary of the ruling Workers’ Party, according to sources inside the country.
The shipyard in the North Hamgyong province capital Cheongjin ceased production of civilian vessels in 2013, when it began to build a “semi-submarine” with a maximum diving depth of 30 meters (100 feet), sources told RFA’s Korean Service earlier this year. The ship could reportedly stay underwater for three days at a time.
The semi-sub was put into military production with a maximum crew of four soldiers when equipped with two torpedoes and 10 soldiers without, and technicians at the shipyard later doubled the vessel’s personnel capacity, earning praise from the country’s leadership.
But sources in North Hamgyong recently told RFA’s Korean Service that the shipyard switched to the manufacture of submarines specifically engineered for troop transport in early 2015 that are far larger and can dive to twice the depth of the earlier vessel.
“Since early this year, Cheongjin Shipyard began manufacturing troop transport submarines that can carry up to 30 [troops], and it is known that they built seven submarines by October,” one source said, speaking on condition of anonymity.
“Cheongjin Shipyard had a plan to build six submarines in 2015, but the factory managers and engineers were determined to produce seven to celebrate the 70th anniversary of the Workers' Party on Oct. 10. The seven submarines have been completed and are undergoing performance testing.”
According to the source, 2,000 laborers and 400 engineers lived at the shipyard, working 16-hour days in order to meet their goal. To aid in their effort, authorities provided the workers with meat, fish, alcohol and confectioneries from the nearby Soosung-Chun Food Factory, he said.
A second source, who also declined to be named, provided information about the new submarine’s specifications.
“The submarine Cheongjin Shipyard is producing measures 40 meters (130 feet) long and four meters (13 feet) wide, and is able to carry nine sailors and 30 combat troops,” he said.
“Also, the submarine can sail for up to 80 hours at a depth of 60 meters (200 feet) in the water.”
The source said each submarine carries only four torpedoes to ensure maximum space for passengers, and that North Korea had imported steel plates from Russia and engines from Germany to build the ships.
He said that the focus on building troop carrier subs, coupled with a standing fleet of Antonov An-2 light aircraft capable of transporting 31 personnel including the pilot, suggests North Korea’s regime is planning an invasion of South Korea simultaneously via sea and air.
In addition to the shipyard, Cheongjin is home to several weapons factories, the source said, including the “May 10 Coal Mine Machinery Factory” which makes rocket launchers, the “Buryeong Precision Machine Factory (No. 42 Factory)” which produces torpedoes, and others.
Submarine incidents
Last month, South Korea’s intelligence service told lawmakers that North Korea had failed in an attempt to test-launch a ballistic missile from a submarine. While the test was unsuccessful, South Korean officials estimate that the North will be able to reliably fire missiles from submarines within five years.
North Korea claimed to have successfully fired a missile from a submarine in May, but some experts believe it was launched from a submerged barge towed by a ship.
Following the launch, the official Korean Central News Agency reported “an underwater test-fire of [North] Korean-style powerful strategic submarine ballistic missile,” adding that the weapon had been developed “on the personal initiative of … [regime leader] Kim Jong Un … and under his meticulous guidance.”
At the time, sources told RFA that the country’s submarine technicians were concerned news of the development could lead South Korean submarines to monitor subs from the North and potentially destroy them before they can launch missiles or, at the least, allow foreign nations to determine the limitations of the technology.
In August, more than 50 of North Korea’s semi-submersible boats—or around 70 percent of the country’s known fleet—disappeared off of military radar and could not be located, South Korea said at the time, stoking fears that the North was poised to attack.
The ships went missing after the two Koreas exchanged live artillery fire over the border, which the South said was initiated by the North, but later returned to their home ports after an agreement was reached to end the escalating stand-off.
Reported by Sung-hui Moon for RFA’s Korean Service. Translated by Hyosun Kim. Written in English by Joshua Lipes.