North Korea has fired an unidentified missile from the Sunan district in its capital, Pyongyang, with the missile passing over Japan.
The Japanese government said the missile had passed over Hokkaido and the country's military did not try to shoot it down.
They issued a nationwide alert - but particularly told residents in the country's north to take shelter.
The South Korean and US militaries are analysing details of the launch.
This is a developing story.
North Korea announced Monday that it successfully tested a “newly-developed ballistic rocket capable of carrying a large-size heavy nuclear warhead,” deepening fears that Kim Jong Un could one day have a weapon capable of hitting the United States.
The test launch Sunday, the tenth so far in 2017, involved a “ground-to-ground medium long-range strategic ballistic rocket Hwasong-12,” according to North Korea’s state media agency KCNA.
North Korea's failed missile was reportedly heading towards Russia before it was detonated mid-flight.
US officials said a medium-range ballistic missile was fired from a region north of the capital of Pyongyang and disintegrated minutes after launch.
The missile was likely to be a medium-range KN-17 ballistic missile, they added, which broke up and fell into the Sea of Japan and did not leave North Korean territory.
The Seoul Economic Daily reports the missile travelled 48 kilometres before officials detonated it over fears it was fired at Russia by accident.
The United States launched dozens of cruise missiles Thursday night at a Syrian airfield in response to what it believes was the Syrian government's use of banned chemical weapons blamed for having killed at least 100 people on Tuesday, U.S. military officials told NBC News.
The U.S. military fired at least 50 Tomahawk missiles intended for a single target — Ash Sha'irat in Homs province in western Syria, the officials said.