North Korea has unveiled a new “tactical nuclear attack submarine,” based on a remodeled Soviet-era vessel, equipped with multiple launching tubes capable of launching nuclear missiles. Submarine No. 841 – named Hero Kim Kun Ok – will be one of the main “underwater offensive means of the naval force” of North Korea, leader Kim Jong Un said at the launch ceremony on Wednesday.

But South Korea’s military expressed skepticism about the submarine on Friday, saying that it “doesn’t look capable of normal operation” and that there were signs of “deception and exaggeration” in the North’s report.

North Korea has been working on developing submarines capable of launching nuclear and other ballistic missiles since at least 2014,  when it unsuccessfully tested a submarine launched missile.   

The United States and its allies have been closely watching the North’s attempts to develop a sub that could launch nuclear and other ballistic missiles. The capabilities of the one introduced this week, originally a Romeo-class Soviet submarine, are unknown​; there is no evidence that North Korea has test-launched a missile from the vessel.
 
Photos released on Friday with the state media report show that the submarine has 10 vertical missile launch tubes of two different sizes​, said Yang Uk, a weapons expert at the Asan Institute for Policy Studies in Seoul. It has an “abnormally large” missile launch deck for its size, as if the North wanted to show off its nuclear force, Mr. Yang said.

That structure “will limit the submarine’s underwater stealthiness and maneuverability,” Mr. Yang added. “Still, the design reflects Kim Jong-un’s policy of increasing his nuclear force ‘exponentially​.’”
 
The submarine is powered by a diesel engine. so unlike a nuclear-powered submarine, it would have to resurface frequently during a long-distance trip, like crossing the Pacific. For a distant adversary like the United States, that makes it more detectable, and less of a threat, than a nuclear-powered sub would be reports the NY Times.

Nevertheless, it could potentially pose a new threat to the North’s regional adversaries, South Korea and Japan​. Choi Il, a retired South Korean Navy submarine captain, said it was designed to carry shorter-range ballistic and cruise missiles that could reach those countries, not strategic ballistic missiles that could target the United States mainland.

North Korea is believed to have a fleet of roughly 70 submarines, most of which are technically obsolete and upwards of 40 years old.

What does North Korea’s ‘nuclear attack submarine’ mean for its navy?

Thanks to Alaric Bond for contributing to this post.