The US, South Korea and Japan detected the launch of the intercontinental ballistic missile (ICBM) - believed to be a new, more agile rocket - which comes just days before the US election.

In a statement released by state media, North Korean leader Kim Jong Un said: "I affirm that the DPRK [North Korea] will never change its line of bolstering up its nuclear forces."

He added the missile launch was "an appropriate military action" after North Korea's "rivals... intentionally escalated the regional situation".

The statement said North Korea had "demonstrated the modernity and creditability of its world's most powerful strategic deterrent".

The launch early on Thursday was the longest ballistic missile test by North Korea, with a flight-time of 87 minutes, according to South Korea.

Seoul's joint chiefs of staff believe the rocket was a new type of solid-fuelled ICBM.

Japan's defence minister Gen Nakatani told reporters the missile's flight duration and its maximum altitude of more than 7,000km (4,350 miles) exceeded previous North Korean missile tests.

It was tracked on a sharply lofted trajectory from an area near Pyongyang and splashed down about 200km
(125 miles) west of Japan's Okushiri island.

North Korea last test-fired an intercontinental ballistic missile in December 2023 when it launched the solid-fuelled Hwasong-18.

Thursday's launch came just hours after US defence secretary Lloyd Austin and his South Korean counterpart Kim Yong-hyun met in Washington to condemn North Korea's troop deployment in Russia.

It has been reported 11,000 soldiers are now in Russia, some close to the frontline in Ukraine. Neither Russia nor North Korea have confirmed the deployment.

A day earlier, Seoul reported signs the North may test-launch an ICBM or nuclear test around the US presidential election on Tuesday, an attempt to draw attention to its military strength.

US national security council spokesperson Sean Savett said the launch "needlessly raises tensions and risks destabilising the security situation in the region".

He added it was "a flagrant violation" of multiple UN Security Council resolutions.

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Both South Korea and Japan also condemned the launch for posing a threat to international peace.

In the past two years, Mr Kim has used Russia's invasion of Ukraine as a window to ramp up weapons tests and threats while also expanding military cooperation with Moscow.

Many foreign experts believe North Korea does not yet have a functioning nuclear-armed missile which can strike the US mainland.

But it is likely short-range missiles could deliver nuclear strikes across all of South Korea.