North Korea said on Saturday it had successfully conducted an underwater test-fire of a submarine-launched ballistic missile, which, if true, would indicate progress in the secretive state's pursuit of building missile-equipped submarines.
An ability to fire ballistic missiles from submarines by the North would pose a significant new threat to South Korea, Japan and the United States that have tried to contain the North's growing nuclear and missile capability, a military expert said.
The North's leader Kim Jong Un oversaw the test-launch from a location off-shore as the submarine dove under water and "a ballistic missile surfaced from the sea and soared into the air, leaving a fiery trail of blaze," official KCNA news agency said.
"Through the test, it was verified and confirmed that the underwater ballistic missile launch from a strategic submarine fully achieved the latest military, scientific and technical requirements," KCNA said.
North Korea is under United Nations sanctions banning it from developing or using ballistic missile technology.
The report did not mention the date or the exact location of the test, but a separate KCNA dispatch on Saturday said Kim gave field guidance at a fishery complex in Sinpo, a port city on the country's east coast and the location of a known submarine base.
A South Korean expert who saw still photos of the launch in the North's news media said they appeared to show a ballistic missile being fired from a submarine in a "cold launch" through an ejection mechanism, a key part of a submarine launch system.
"The potential of this is that existing missile defense against the North can be rendered useless," said Shin In-kyun, a military expert who runs the Korea Defence Network, an independent forum.
The added challenge would be the difficulty of detecting and intercepting submarine-launched ballistic missiles using systems that are basically positioned to look at the North, not at "submarines that could be south of Jeju or near Guam."
Jeju is a South Korean island off its southern mainland.
Shin said a full deployment of the submarine-based missile system would still require a functional guided propulsion mechanism that can carry the vehicle from the surface of the water to a target.
The North has also yet to demonstrate it has successfully miniaturized a nuclear warhead to be fitted on a delivery vehicle for deployment, according to experts.
South Korea did not have an immediate comment on the report on the North's submarine launch.
In January, Johns Hopkins University's U.S.-Korea Institute said on its website, 38 North, that satellite imagery showed possible evidence of work on vertical launch tubes on a submarine that could be for ballistic missiles.
The vessel could serve "as an experimental test bed for land-attack submarines", 38 North said in a report, although it cautioned such a test would be expensive and time-consuming "with no guarantee of success".
North Korea's state media often boasts of successful military and space accomplishments, including the launch of a functional communications satellite, which do not get independently verified by outside experts.
But it is widely believed to have succeeded in launching a long-range rocket and putting an object into orbit in December 2012 defying widespread scepticism and international warnings not to pursue such a program, which could be used to develop intercontinental missiles.
South Korea's military said later on Saturday the North fired three land-based cruise missiles from a separate location on its east coast into the sea with a range of about 120 km (72 miles). The North has occasionally fired similar missiles.
The North has an arsenal of land-based ballistic missiles and last test-fired a mid-range missile in March last year, drawing further condemnation from the international community.
