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's claim of what it called a successful launch of a new intermediate-range ballistic missile (IRBM) tipped with a hypersonic warhead is presumed to be "deception," South Korea's military said Tuesday.

The assessment came hours after North Korea said it successfully test-fired the missile the previous day, saying it flew some 1,500 kilometers at 12 times the speed of sound.

kilometers ea's Joint Chiefs of Staff (JCS) earlier said the IRBM launched from the Pyongyang area flew about 1,100 kilometers before falling into the East Sea.

"It is assessed that North Korea's claim of the flight distance and the second peak altitude is highly likely deception," JCS spokesperson Col. Lee Sung-jun told a regular briefing.

"The flight range analyzed by South Korea, the United States and Japan is around 1,100 kilometers and (the missile) did not reach a second peak," Lee said, dismissing the North's claim that the missile reached the second peak at 42.5 kilometers.

When asked about whether the North could have received technological assistance from Russia in developing the new missile, the JCS official did not rule out such possibility.

North Korea claimed Tuesday that it has accomplished technological advancements, such as using a "new compound of carbon fiber" for the engine body, raising suspicions of technological aid from Russia amid their growing military alignment.

The latest launch came around nine months after the North launched an IRBM tipped with a hypersonic warhead in April. At that time, Pyongyang claimed the "powerful, strategic offensive weapon" made a 1,000-kilometers -long flight as planned.

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

North Korea first test-fired a missile tipped with a hypersonic glide vehicle in September 2021, although that launch was seen as a failure.

The North has been seeking to develop sophisticated weapons, such as hypersonic missiles, nuclear-powered submarines, spy satellites and solid-fuel intercontinental ballistic missiles, after leader Kim Jong-un vowed to develop them in a key party congress in 2021. (Yonhap)