That is what this Voice of America article brings up:
North Korean leader Kim Jong Un (L) stands on the conning tower of a submarine during his inspection of the Korean People’s Army (KPA) Naval Unit 167 in this undated photo released by North Korea’s Korean Central News Agency (KCNA) in Pyongyang.
South Korean officials Monday outlined their worries about North Korea’s first test missile launch from a submarine. Although the test does not immediately change the military status quo on the Korean peninsula, it shows Pyongyang is working on a difficult-to-detect missile system that could become capable of threatening countries around the world.
South Korean Defense Ministry spokesman Kim Min-seok confirmed that North Korea did test-fire an underwater ballistic missile on May 8. He called the test a serious and great concern and urged Pyongyang to immediately stop further development of this weapon. But the defense ministry spokesman also said the test indicates North Korea is years away from deploying this enhanced capability.
He said the ministry’s view is that North Korea’s test-fire this time shows it is in the early stage of development of a submarine launched ballistic missile program. According to the cases of advanced countries, he said, it takes about four to five years after the underwater test to complete the development of the system.
Still, the fact that Pyongyang is on a trajectory to develop a submarine based missile system means it could develop the capability to strike anywhere in the world, including the mainland of the United States.
This new capability would make less effective South Korea’s current Kill Chain missile system, intended to target and destroy North Korean missile launch sites.
The increased North Korean threat could trigger a new arms race on the Korean peninsula. It could also be used to justify the deployment of the United States anti-ballistic missile system called THAAD. Seoul had been reluctant to accept THAAD in part because China opposes its deployment. [Voice of America]
You can read more at the link, but since the development of an actual working missile launched from a submarine is years away I don’t think this gives the ROK the cover it needs to allow the US to deploy THAAD to Korea against China’s wishes.
