Japan furious after North Korean missile launch

North Korea has fired at least one unidentified ballistic missile eastward, according to South Korea's Joint Chiefs of Staff (JCS).

According to CNN's count, today's launch marks North Korea's 23rd missile launch this year, including both ballistic and cruise missiles.

The suspected missile launch sparked a warning from the Japanese government urging citizens to "evacuate inside a building or underground".

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"The aforementioned missile is believed to have passed through the Pacific Ocean around 07.29am JST (9.29am AEDT)," the premier's office said in another tweet.

The statement urged civilians in Japan "to not approach anything suspicious that is found and to immediately contact the police or fire department."

It's believed the missile passed over the northern Japanese island of Hokkaido, before landing in the Pacific Ocean.

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The same island was beneath the flight path of North Korea's last missile launched over Japanese territory, in 2017.

The Japanese government is convening its security council to discuss a response.

Officials said the country "strongly objects" to the launch and will "protest" it.

There have been no reports of damage to ships following the missile crashing into the ocean.

Japan will work with South Korea and the US to respond to the missile launch.

The launch is the fifth round of weapons testing by North Korean in the past 10 days, in what was seen as an apparent response to military drills between South Korea and the US.

North Korea views such drills as an invasion rehearsal.

The missiles fired during the past four rounds of launches were short-range and fell in the waters between the Korean Peninsula and Japan.

Those missiles are capable of hitting targets in South Korea.