North Korea says leader Kim supervised tests of cruise missiles designed to be fired from submarines

North Korean leader Kim Jong Un supervised test firings of new cruise missiles designed to be launched from submarines and also reviewed efforts to build a nuclear-powered submarine while reiterating his goal of building a nuclear-armed navy to counter what he portrays as growing external threats, state media said Monday.

The report came a day after South Korea’s military said it detected North Korea firing multiple cruise missiles over waters near the eastern port of Sinpo, where the North has a major shipyard developing submarines. It was the latest in a streak of weapons demonstrations by North Korea amid increasing tensions with the United States, South Korea and Japan.

North Korea’s official newspaper Rodong Sinmun published photos of what appeared to be at least two missiles fired separately. Both created grayish-white clouds as they broke the water surface and soared into the air at an angle of around 45 degrees, which possibly suggests they were fired from torpedo launch tubes.

State media said the missiles were Pulhwasal-3-31, a new type of weapon first tested last week in land-based launches from North Korea's western coast.

The reports implied that two missiles were fired during the test. KCNA said the missiles flew more than two hours before accurately striking an island target, but it did not specify the vessel used for the launches. North Korea in past years has fired missiles both from developmental, missile-firing submarines and underwater test platforms built on barges.

Lee Sung Joon, spokesperson of South Korea’s Joint Chiefs of Staff, said the South Korean and U.S. militaries were analyzing the launches, including the possibility that the North exaggerated the flight times.

In recent years, North Korea has tested a variety of missiles designed to be fired from submarines as it pursues the ability to conduct nuclear strikes from underwater. In theory, such capacity would bolster its deterrent by ensuring a survivable capability to retaliate after absorbing a nuclear attack on land.

Missile-firing submarines would also add a maritime threat to the North’s growing collection of solid-fuel weapons fired from land vehicles that are designed to overwhelm missile defenses of South Korea, Japan and the United States.

Still, it would take considerable time, resources and technological improvements for the heavily sanctioned nation to build a fleet of at least several submarines that could travel quietly and execute attacks reliably, analysts say.

The North’s official Korean Central News Agency said Kim expressed satisfaction after the missiles accurately hit their sea targets during Sunday’s test.

He then issued unspecified important tasks for “realizing the nuclear weaponization of the navy and expanding the sphere of operation,” which he described as crucial goals considering the “prevailing situation and future threats,” the report said. KCNA said Kim was also briefed on efforts to develop a nuclear-propelled submarine and other advanced naval vessels.

Kim issued similar comments about a nuclear-armed navy in September while attending the launching ceremoney of what the North described as a new submarine capable of firing tactical nuclear weapons from underwater. He said then that the country was pursuing a nuclear-propelled submarine and that it plans to remodel existing submarines and surface vessels so they can handle nuclear weapons.

Nuclear-propelled submarines can quietly travel long distances and approach enemy shores to deliver strikes, which would bolster Kim's declared aim of building a nuclear arsenal that could viably threaten the U.S. mainland. But experts say such vessels are likely unfeasible for the North without external assistance in the near-term.

North Korea has an estimated 70 to 90 diesel-powered submarines in one of the world’s largest submarine fleets. But they are mostly aging vessels capable of launching only torpedoes and mines.

South Korea’s military said the submarine unveiled by North Korea in September, the “Hero Kim Kun Ok,” didn't look ready for operational duty and suggested the North was exaggerating its capabilities.

The submarine appeared to have at least 10 launch tubes possibly designed for missiles. The South’s Joint Chiefs of Staff said that the North would have needed to increase the size of the bridge and other parts of the original vessel to accommodate missile launch systems, but that the appearance of the vessel suggested it could “not be operated normally.”

Tensions on the Korean Peninsula have increased in recent months as Kim accelerates his weapons development and issues provocative threats of nuclear conflict with the U.S. and its Asian allies.

The U.S., South Korea and Japan in response have been expanding their combined military exercises, which Kim condemns as invasion rehearsals, and sharpening their deterrence strategies built around nuclear-capable U.S. assets.

The recent cruise missile launches followed a Jan. 14 test firing of North Korea's first solid-fuel intermediate-range ballistic missile, which reflected Kim's efforts to expand his arsenal of weapons designed to overwhelm missile defenses in South Korea and Japan and remote U.S. targets in the Pacific, including Guam.