Kim Jong Un vows to boost nuke capability after observing new ICBM launch

North Korean leader Kim Jong Un vowed to further bolster his country's nuclear fighting capabilities as he supervised the country's second test-flight of a new intercontinental ballistic missile designed to strike the mainland US, state media reported Thursday.

Kim's statement suggests North Korea would ramp up weapons testing activities to expand its arsenals in response to recent US steps to enhance its security commitment to ally South Korea.

"The present unstable situation in which the security environment on the Korean peninsula is being seriously threatened by the hostile forces every moment," Kim said, according to state media. "(That) requires more intense efforts to implement the line of bolstering nuclear war deterrent."

The Korean Central News Agency disclosed Kim's comments, after confirming the North conducted a successful launch of the Hwasong-18 ICBM on Wednesday. The launch was first reported by its neighbours soon after its liftoff.

The Hwasong-18 is a developmental, road-mobile missile, whose built-in solid propellant make it more difficult for opponents to detect its launches in advance than liquid-fueled missiles. North Korea first tested the missile in April, and Kim has called it the most powerful weapon of his nuclear forces.

KCNA said the launch was meant to reconfirm the technical credibility and operational reliability of the missile. Kim called the launch "another important stride" in efforts to boost the North's strategic forces, KCNA said.

According to KCNA, the missile was launched on a high angle to avoid neighbouring countries. It said the weapon travelled 74 minutes and a distance of 1,001 kilometres (622 miles) at a maximum altitude of 6,648 kilometres (4,130 miles) before landing on the preset area in the open waters off the North's east coast.

The missile's flight time is the longest-ever recorded by any weapon launched by North Korea. If launched on a standard trajectory, the missile could fly to the mainland US though some experts say North Korea still has some technologies to master to acquire functioning nuclear-armed missiles.

South Korea, Japan and the United States criticised North Korea over the launch that they said posed a threat to regional and international peace. Adam Hodge, a spokesperson for the White House National Security Council, said in a statement that the US will take all necessary steps to ensure the security of the American homeland and South Korean and Japanese allies.

Kim set for unspecified tasks for the North's national defence sector, saying North Korea will take "a series of stronger military offensive" until the US and South Korea "admit their shameful defeat of their useless hostile policy toward (North Korea) in despair and give up their policy."

That signals Kim will intensify his push to modernise his missile arsenals with sophisticated weapons like the Hwasong-18. Other weapons on Kim's publicly stated wish list are a multi-warhead missile, a hypersonic weapon, a spy satellite and a nuclear-powered submarine.

North Korea has been focusing on reinforcing its nuclear capability after Kim's high-stakes nuclear diplomacy with then President Donald Trump collapsed in 2019 due to disputes over US-led sanctions on North Korea.

KCNA accused the US and South Korea of recently taking "frantic confrontation attempts" and bringing "a new chain of nuclear crises" on the Korean Peninsula.

North Korea often issues such harsh, warlike rhetoric in times of tensions with its rivals. The KCNA dispatch cited a US-South Korean agreement to strengthen the allies' deterrence capabilities such as the periodic docking of a US nuclear-armed submarine in South Korea and the establishment of a new bilateral nuclear consultative group, whose inaugural meeting is slated for next week in Seoul.

The United States has expanded military drills with South Korea and taken steps to enhance "regular visibility" of US strategic assets to the Korean Peninsula in response to the North's advancing nuclear arsenal. North Korea conducted about 100 missile tests since the start of last year. Experts say Kim eventually aims to use his enlarged arsenal to win greater concessions in future diplomacy with the United States.

Wednesday's ICBM launch came two days after Kim's sister and senior adviser, Kim Yo Jong, threatened "shocking" consequences to protest what she called provocative United States reconnaissance activity near its territory.

The US and South Korean government dismissed the North's accusation groundless and urged it to refrain from escalatory actions.