South Korea is always prepared to defend itself against North Korea.

South Korea believes North Korea may have launched a ballistic missile from a submarine off its east coast today.

North Korea may have launched a ballistic missile from a submarine today. (Illustrative image: KCNA)

"North Korea launched what is believed to be a submarine-launched ballistic missile (SLBM) at around 6:30 p.m. (9:30 GMT) near the port city of Sinpo," in northeastern North Korea, AFP quoted a South Korean Defense Ministry spokesman as saying.

The source said South Korea is closely monitoring the North Korean military and remains on high alert. The South Korean Ministry of Defense could not confirm whether the launch was successful.

According to a South Korean government source, the SLBM's engine caught fire after it was launched from a Sinpo-class submarine, but it only traveled a short distance.

North Korea is believed to be seeking to acquire SLBMs, which would allow Pyongyang to deploy them further and enhance its ability to retaliate in the event of a nuclear attack.

North Korea first announced a successful SLBM test in May 2015, posting images of leader Kim Jong-un pointing at the missile as it launched from underwater. Many experts believe the images were digitally altered and that the test was merely a test of the missile's ability to leave the launch tube, and that the missile was launched from a submerged platform, not a submarine.

According to VNE