The North fired the missile to the northeast from an area off its east coast at about 0930 GMT.
Today, South Korea has said that North Korea fired a submarine-launched ballistic missile (SLBM) off its east coast. South Korea also expressed concern that North Korea might conduct a nuclear test of a missile launch ahead of the key ruling party meeting in May.
The South’s office of the Joint Chiefs of Staff said the North fired the missile to the northeast from an area off its east coast at about 0930 GMT.
For the first time in 36 years, North Korea will hold a rare congress of its ruling Workers’ Party in early May.
The US and South believe that the North is working to develop a submarine-launched ballistic missile system and an intercontinental ballistic missile putting the mainland United States within range.
Tensions have escalated since the start of 2016 after the North’s nuclear test in January and a long-range rocket launch on February 7. North Korea said that the rocket launch was aimed at placing an earth observation satellite into orbit but Washington and Seoul argued the move was a cover for an intercontinental ballistic missile test.
The US occasionally deploys nuclear-powered warships and aircraft capable of carrying atomic weapons in the region. In response, North Korea has vowed to develop a nuclear arsenal in an effort to protect itself from the US military.
However, the Korean Peninsula has been locked in a cycle of military tensions since the 1950-1953 Korean War, which ended in a truce. Since no peace deal has been signed; technically the two Koreas remain at war.