SEOUL: North Korea said Thursday it had test-fired one of its newest and most powerful missiles to boost its nuclear deterrent, Kim Jong Un’s first weapons test since being accused of sending soldiers to Russia.

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.

“The initial judgment so far is that (Pyongyang) may have test-fired a new solid-propelled long-range ballistic missile,” Seoul’s military said, adding the missile had flown around 1,000 kilometres (621 miles) after being fired on a lofted trajectory — meaning up, not out.

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.

The test “updated the recent records of the strategic missile capability,” of North Korea, it said, with Kim vowing his country “will never change its line of bolstering up its nuclear forces”.

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.

“We estimate that its flying altitude was the highest we have seen,” Japanese defence minister Gen Nakatani told reporters.

Washington slammed the launch as “a flagrant violation of multiple UN Security Council resolutions”, National Security Council spokesman Sean Savett said in a statement.