Military officials in South Korea say it was launched at about 11:30am local time
North Korea has test-fired a submarine-launched ballistic missile, according to the South Korean Military.
Officials say it was launched in waters to the east of the Korean peninsula, but appears to have failed in the early stages of flight.
Reuters reports that the launch comes a day after the US and South Korea pledged to deploy an advanced anti-missile system to counter threats from the capital, Pyongyang.
Two days after North Korea warned it was planning its toughest response to what it deemed a "declaration of war" by the United States.
Speaking to the news agency Kyodo, the Japanese Prime Minister Shinzo Abe called the launch a 'clear challenge' of UN resolutions.
"We should strongly condemn the launch by working with the international community."