North Korea’s leader, Kim Jong-un, watched the country’s newest 5000-tonne destroyer capsize during its launch last week in an embarrassing military failure. Experts say a technique used to manoeuvre the ship into the water sideways was part of the problem.

It was the first time analysts had observed North Korea using the sideways launch for warships and pointed to a lack of experience, as well as political pressure from Kim for quick results, for the mishap. Three shipyard officials, including the chief shipyard engineer and a senior munitions official, have been arrested, the official Korean Central News Agency reported, after Kim called the capsizing a criminal act.

Satellite imagery from three days before the accident showed the 143-metre-long vessel, the biggest class of warships North Korea has ever built, on top of a launch ramp. About 40 metres from the ship, a structure that appeared to be a viewing area and likely where Kim was stationed during the incident was under construction.

The destroyer was assembled in Chongjin, a port city on North Korea’s north-eastern coast, which is known for producing smaller vessels, such as cargo ships and fishing boats. In a report published by the Centre for Strategic and International Studies, a research institute in Washington, analysts said the shipyard “undoubtedly” lacked expertise in manufacturing and launching large warships.

The ill-fated warship was assessed by analysts to be the same size and configuration as the Choe Hyon guided missile destroyer, the North’s first destroyer and the most powerful surface ship the country has ever built. That vessel is the pride of Kim’s ambitious plan to modernise and expand his Soviet-era naval fleet, and was the centrepiece of a grand christening ceremony last month in Nampo, a west coast port near Pyongyang.

State media footage showed an elaborate event with confetti and fireworks that was attended by Kim and his daughter, Kim Ju-ae. A large viewing platform was set up near the Choe Hyun, which was already afloat in the water.

That launch went smoothly, according to state media. Engineers used a technique common for large and heavy vessels. They appear to have built the Choe Hyun inside a roofed construction hall in Nampo, brought it out on a floating dry dock and then set it afloat by letting water into the dry dock, said Choi Il, a retired South Korean navy captain.

‘The ship looks a bit twisted after the accident. It doesn’t appear to have been built with the structural strength required for a warship.’

Yang Uk, Asian Institute for Policy Studies, Seoul

But the shipyard in Chongjin didn’t have a dry dock large enough to build a Choe Hyun-class destroyer, nor an incline to slide the ship stern first into the water. Engineers built the ship on the quay under a netting. When it was completed, they had to launch it sideways off the platform.

When properly executed, the vessel glides down the slipway lengthwise and briefly plunges into the water.

Often, a tugboat is stationed nearby to assist after the launch.

But when engineers tried to push the North Korean destroyer into the water, it lost its balance, state media said. Satellite imagery taken two days after the accident showed the ship covered in blue tarpaulins and lying on its right side. The bow was stuck on the ramp as the stern jutted into the harbour. The viewing platform had been removed.

Launching big ships sideways requires delicate balancing work, Choi said. The heavy weapons mounted on the destroyer could have made the task even more difficult, he added.

A few days after the first Choe Hyun-class destroyer was launched last month, Kim proudly watched it test-fire various missiles. He has visited shipyards to exhort engineers to meet his timetable for naval expansion and appears to have planned to launch the second destroyer with similar fanfare and weapons tests.

Engineers at Chongjin, who worked with less developed facilities than their peers in Nampo, must have felt enormous pressure after the successful launch in Nampo, South Korean analysts said. That might have led them to cut corners, they said.

North Korea has said that it can restore the ship’s balance by pumping out the seawater. In another 10 days or so, it could repair the ship’s side damaged in the accident, according to state media.

But the damage looked worse than the country claimed, said Yang Uk, an expert on the North Korean military at the Asian Institute for Policy Studies in Seoul, South Korea. The accident may be due not only to a defective sideways launching system but also to the ship’s structural imbalance, he said.

“The ship looks a bit twisted after the accident,” he said. “It doesn’t appear to have been built with the structural strength required for a warship.”

This article originally appeared in The New York Times.

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