The North Korean state media report came a day after South Korea's military said it detected North Korea launching a missile that flew 1,100 kilometres before landing in waters between the Korean Peninsula and Japan.
In recent years North Korea has flight tested various intermediate-range missiles, which if perfected, could reach the US Pacific military hub of Guam. In recent months, it has been testing combining these missiles with purported hypersonic warheads to improve their survivability.
The North's state media said Kim supervised Monday's launch, and that the weapon travelled 1,500 kilometres during which it reached two different peaks of 99.8 kilometres and 42.5 kilometres and achieved a speed amounting to 12 times the speed of sound, before accurately striking a sea target.
Lee Sung Joon, spokesperson of South Korea's Joint Chiefs of Staff, said the South Korean military believes North Korea is exaggerating the system's capabilities, saying the missile covered less distance and that there was no second peak.
Lee said it would be difficult to use such systems in a relatively small territory like the Korean Peninsula. He said the South Korean and US militaries were continuing to analyse the missile.
Kim described the missile as a crucial achievement in bolstering the North's nuclear deterrence by building an arsenal "no one can respond to," according to the official Korean Central News Agency.
"The hypersonic missile system will reliably contain any rivals in the Pacific region that can affect the security of our state," the agency quoted Kim as saying.
The launch took place while US Secretary of State Antony Blinken was visiting Seoul for talks with South Korean allies over the North Korean nuclear threat and other issues.
In a news conference with South Korean Foreign Minister Cho Tae-yul on Monday, Blinken condemned North Korea's launch, which violated UN Security Council resolutions against the North's weapons programs.
He also reiterated concerns about the growing alignment between North Korea and Russia in Moscow's war on Ukraine.
According to US, Ukrainian and South Korean assessments, North Korea has sent more than 10,000 troops and conventional weapons systems to support Moscow's war campaign. There are concerns that Russia could transfer to North Korea advanced weapons technology in return, which could potentially enhance the threat posed by Kim's nuclear-armed military.
During his first term as president, Donald Trump met Kim three times for talks on the North's nuclear program.
However, when Trump returns to the White House, a quick resumption of diplomacy with North Korea could be unlikely.
Kim's strengthened position — built on his expanded nuclear arsenal, deepening alliance with Russia and the weakening enforcement of US international sanctions — presents new challenges to resolving the nuclear standoff, experts say.
