North Korea has fired another missile, which passed over northern Japan earlier today, the Japanese government says.
The government's J-Alert warning system advised people in the area to take precautions, but public broadcaster NHK said there was no sign of damage.
The Japanese military did not attempt to shoot down the missile, which passed over Japanese territory about 6.06am local time (9.06am NZT).
NHK reported that the missile broke into three pieces and fell into the waters off Japan's Hokkaido.
South Korea's military said the projectile was fired from the Sunan region near the North Korean capital of Pyongyang.
It said the missile flew about 2700km and reached an altitude of about 550km.
Japan's chief cabinet secretary, Yoshihide Suga, said that North Korea's latest launch was a threat that Tokyo would respond to firmly.
"This ballistic missile launch appeared to fly over our territory. It is an unprecedented, serious and grave threat to our nation," the top government spokesman told reporters.
Japan protested the firing in the strongest terms, Mr Suga said, calling a clear violation of United Nations resolutions.
He said Japan would work closely with the United States, South Korea and other concerned nations to take a "timely and appropriate response".
Tensions had eased between North Korea and the United States after weeks of threats.
North Korean leader Kim Jong Un threatened to fire missiles into the sea near the US Pacific territory of Guam and US President Donald Trump warned Pyongyang would face "fire and fury" if it threatened the United States.
The Pentagon said today's missile flight did not pose a threat to North America.
"We can confirm that the missile launched by North Korea flew over Japan," Pentagon spokesman Colonel Robert Manning told reporters. He said that the US military was gathering further information.