"North Korea launched a projectile which was believed to be a submarine-launched ballistic missile around 6:30 pm (0930 GMT) in the East Sea (Sea of Japan) near the north-eastern port of Sinpo," a South Korea defence ministry spokesman said.
"We are keeping close tabs on the North Korean military and maintaining a full defence posture," he said.
http://www.bbc.com/news/world-asia-36119159