This photo, carried by North Korea's official Korean Central News Agency on Jan. 7, shows the test-firing of a new intermediate-range hypersonic ballistic missile the previous day. Yonhap

North Korea said Tuesday it has successfully test-fired a new intermediate-range ballistic missile (IRBM) tipped with a hypersonic warhead, claiming that the weapons system will reliably deter any rivals in the Pacific region.

But the South Korean military said the North's claimed success of a hypersonic missile launch could be "deception," raising questions about its flight distance and other specifications.

North Korea said the missile flew some 1,500 kilometers at 12 times the speed of sound the previous day during the testing overseen by leader Kim Jong-un via a monitoring system, according to the Korean Central News Agency (KCNA).

The South's Joint Chiefs of Staff (JCS) said Monday the North's suspected hypersonic missile, fired from the Pyongyang area, flew about 1,100 km before falling into the East Sea.

The North Korean leader said the development of such a missile was aimed at bolstering the country's nuclear war deterrent by "making the weapon system to which no one can respond the linchpin of strategic deterrence."

"The hypersonic missile system will reliably contain any rivals in the Pacific region that can affect the security of our state," Kim was quoted as saying by the KCNA.

"The system can deal a serious military strike to a rival while effectively breaking any dense defensive barrier," he added.

The North's latest missile launch, the first provocation in about two months, came about two weeks before U.S. President-elect Donald Trump takes office Jan. 20.

It also came amid political turmoil in South Korea sparked by President Yoon Suk Yeol's botched martial law imposition last month and his subsequent impeachment by the National Assembly.

"North Korea probably intended to flex its muscle against the United States. As it said the latest launch was a test-firing, the weapons system does not appear to be completed, pointing to demand (to further develop) in terms of military technology," an official at South Korea's unification ministry told reporters.

A hypersonic missile is usually hard to intercept with existing missile defense shields. It travels at a speed of at least Mach 5 — five times the speed of sound — and is designed to be maneuverable on unpredictable flight paths and fly at low altitudes.

The KCNA said the hypersonic glide vehicle atop the new IRBM reached its first peak at a height of 99.8 km and the second at 42.5 km while making a 1,500-km-long flight as scheduled before hitting a designated target point at sea.

This photo, carried by North Korea's official Korean Central News Agency on Jan. 7, shows leader Kim Jong-un, center, overseeing the test-firing of a new intermediate-range hypersonic ballistic missile via a monitoring system the previous day. Yonhap

But the South Korean military dismissed the North's claim as a "deception," saying there was no second peak.

"The flight range analyzed by South Korea, the U.S. and Japan was around 1,100 km and (the missile) did not reach a second peak," JCS spokesperson Col. Lee Sung-un told a regular press briefing, noting the North has a track record of "exaggerating."

North Korea also claimed a new compound of carbon fiber was used in manufacturing the engine body of the hypersonic missile, and an unspecified "comprehensive and effective" method was introduced for the flight and guidance control system.

Experts said the North appeared to fire the upgraded version this week of a hypersonic missile that it launched in April last year. Pyongyang then claimed the IRBM loaded with a hypersonic glide vehicle flew 1,000 km.

The South's JCS then said the missile flew 600 km, calling the North's claims partially "exaggerated," although it said Pyongyang appears to have made some technological progress in its hypersonic weapons program.

"As the North has claimed it has acquired technology that is 'by no means easy,' there could be a technical improvement of its own. But it is also hard to exclude the possibility of technical cooperation from Russia," Hong Min, a senior research fellow at the Korea Institute for National Unification, said.

North Korea and Russia have been deepening military cooperation under a mutual defense treaty signed in June, with the North accused of sending more than 11,000 troops to Russia to support its war against Ukraine.

Hypersonic missiles are among the sophisticated weapons Kim vowed to develop during a key party congress in 2021, along with nuclear-powered submarines, spy satellites and solid-fuel intercontinental ballistic missiles.

At a year-end party meeting, the North's leader said his country would carry out the "toughest" counteraction strategy toward the U.S. and claimed that military cooperation among South Korea, the U.S. and Japan has expanded into a "military bloc for aggression." (Yonhap)