Japan's top government spokesperson says the latest ballistic missile launched by North Korea is believed to be intermediate-range.

North Korea says it successfully test-fired a solid-fuel intermediate-range ballistic missile on Sunday. It claims the missile had a warhead that travels at hypersonic speeds.

Solid-fuel missiles can be launched more quickly than liquid-fuel ones.

Chief Cabinet Secretary Hayashi Yoshimasa told reporters on Monday that the Defense Ministry is analyzing the details, including whether the missile was a hypersonic weapon.

He said that hypersonic weapons, in general, take more time to detect using radars and are more difficult to intercept.

Hayashi acknowledged North Korea's potential to take further provocative actions, including launches of various missiles, and said Japan will keep working closely with the US and South Korea to monitor the situation.

Hayashi also referred to a mechanism activated by the three countries last month to share real-time data on North Korean missile launches. He said the countries have been sharing information, including how to deal with the latest launch, around the clock.