South Korea’s military expressed deep worry Monday about the Democratic People’s Republic of Korea(DPRK) ’s test-firing of a ballistic missile from its submarine

South Korea's military expressed deep worry Monday about the Democratic People's Republic of Korea(DPRK) 's test-firing of a ballistic missile from its submarine.

"Our military is deeply and seriously worried about the underwater test-firing of a ballistic missile conducted by North Korea (DPRK) last week," Defense Ministry spokesman Kim Min-seok told a regular press briefing.

Kim urged Pyongyang to immediately stop developing the submarine-launched ballistic missile (SLBM) that would destabilize the Korean Peninsula and the Northeast Asian region.

The DPRK's official KCNA news agency reported Saturday that it succeeded in test-firing a ballistic missile from a submarine, which was overseen by top leader Kim Jong Un.

The DPRK's SLBM could mean more powerful nuclear threats to the U.S. mainland as well as South Korea because the fully-developed SLBM would mean a DPRK submarine secretly sailing underwater to the U.S. waters and firing ballistic missiles to strike major military facilities and the mainland.

Regarding the worry, the spokesman said that the DPRK's submarines can be detected with South Korea's existing surveillance assets and can be tackled with its own submarines and missiles.

Kim, however, said that if the DPRK's submarines sail underwater, it would be hard to find where it is, noting that the submarines could be tackled before going underwater.