North Korea arrests senior official over warship launch failure

North Korea has arrested a fourth official over the failed launch of a new warship that has enraged the country's leader, Kim Jong Un.

Ri Hyong-son, deputy director of the ruling Workers' Party's Munitions Industry Department, was "largely responsible for the serious accident" last week, state-run news agency KCNA said on Monday.

The 5,000-ton destroyer had tipped over and damaged its hull, in what Kim had described as a "criminal act" that "severely damaged the [country's] dignity and pride".

The vessel is being repaired under the guidance of an expert group, KCNA said.

Mr Ri, who is part of the party's Central Military Commission, is the highest level official arrested over the incident so far.

The commission commands the Korean People's Army and is responsible for developing and implementing North Korea's military policies.

Over the weekend, Pyongyang also detained three officials at the northern Chongjin shipyard, where the destroyer was built and where its launch failed.

The officials were the chief engineer, its construction head and an administrative manager.

Kim earlier said Wednesday's incident was caused by "absolute carelessness, irresponsibility and unscientific empiricism".

It is not clear what punishment they might face, but the authoritarian state has been known to sentence officials it finds guilty of wrongdoing to forced labour and even death.

It is uncommon for North Korea to publicly disclose local accidents, though it has done this a handful of times in the past after failed satellite launches.

Some analysts believe Kim's swift and severe response was meant as a signal that Pyongyang will continue to advance its military capabilities.

"This sends a clear message to South Korea and the US that North Korea isn't going to stop in trying to repair and strengthen its naval technology," Edward Howell, a North Korea expert at Oxford University told ABC news.

A commentary on Seoul-based Daily NK, a news outlet focussing on North Korea, suggests that Kim's "transparency, however reluctant" shows he views naval modernisation as such a critical priority, and that "even public failures cannot derail the broader narrative of military advancement".

Last week's shipyard accident comes weeks after North Korea unveiled a similar warship in another part of the country.

Kim had called that warship a "breakthrough" in modernising North Korea's navy and said it would be deployed early next year.