Seoul had warned a day earlier that the nuclear-armed North was preparing to test-fire another intercontinental ballistic missile (ICBM) or even conduct a nuclear test ahead of next week's US elections. The launch came just hours after US and South Korean defence chiefs called on Pyongyang to withdraw its troops from Russia, warning that North Korean soldiers in Russian uniforms were being deployed for possible action against Ukraine.

Developing advanced solid-fuel missiles -- which are quicker to launch and harder to detect and destroy in advance -- has long been a goal for Kim.

North Korea defended the sanctions-busting launch, calling it "an appropriate military action that fully meets the purpose of informing the rivals... of our counteraction will," the official Korean Central News Agency reported Kim as saying.

Tokyo said that the "ICBM-class" missile had flown for longer than any other previously tested by the North, being airborne for about 86 minutes and hitting altitudes of 7,000 kilometres.

North Korea's missile launch "seems to have been carried out to divert attention from international criticism of its troop deployment," Yang Moo-jin, president of the University of North Korean Studies in Seoul, told AFP.