The test was detected on Thursday by South Korea and Japan, which briefly ordered residents on its northern island of Hokkaido to evacuate.
North Korean state media confirmed the launch of the missile, dubbed the Hwasong-18, on Friday morning.
The event was supervised by Kim, who was accompanied by his wife, young daughter and powerful sister Kim Yo Jong.
“A new type of intercontinental ballistic missile was test fired on Thursday as the key means of strategic military force,” the official Korean Central News Agency (KCNA) said, describing the test as a “miraculous success”.
The news agency cited Kim as saying the Hwasong-18 would rapidly advance North Korea’s nuclear response posture and further support an aggressive military strategy that promises to maintain “nuke for nuke and an all-out confrontation for an all-out confrontation” against its rivals.
“The Hwasong-18 weapons system to be run by the country’s strategic forces would play its mission and role to defend (North Korea), deter invasions and preserve the country’s safety as its most powerful method,” KCNA said.
Solid fuel missiles are safer to use, easier to manoeuvre and faster to deploy than liquid-propelled variants, which need to be loaded at the launch site and were a key part of a five-year arms development plan Kim unveiled in 2021.
Kim Jong Un and his daughter looking upwards as the missile takes off. They are standing side by side in a tent. here is a military official beside Kim Kong Un.
Despite a United Nations ban on ballistic missile testing, North Korea has carried out numerous launches in recent years as it looks to advance its military prowess.
Last year, it tested a record number of weapons, including a high-thrust solid-fuel engine, and in February displayed what looked to be a new ICBM at a lavish night-time parade in Pyongyang.
“This is a significant breakthrough for the North Koreans, but not an unexpected one,” said Ankit Panda, an expert with the Carnegie Endowment for International Peace.
“Because these missiles are fuelled at the time of manufacture and are thus ready to use as needed, they will be much more rapidly useable in a crisis or conflict, depriving South Korea and the United States of valuable time that could be useful to preemptively hunt and destroy such missiles.”
North Korea has pointed to large-scale military exercises between South Korea and the United States to justify its latest spate of tests, claiming such drills are rehearsals for invasion.
Washington and Seoul say their drills are defensive in nature and a result of North Korea’s growing nuclear and missile threats.
The Hwasong-18 launch comes two days before the country commemorates the birth of founder Kim Il Sung, one of North Korea’s most important holidays.
Leif-Eric Easley, a professor at Ewha University in Seoul, said the days of North Korea disguising ICBM activity as satellite launches were long-gone and that Kim’s “blatant violations” of UN Security Council resolutions showed that his goal was to “make North Korea a full-fledged nuclear power and demand concessions from other countries”.
Denuclearisation talks have been stalled since 2019 when a high-profile summit between Kim and then-US President Donald Trump collapsed.
The Hwasong-18, which KCNA described as a three-stage missile, was fired from near Pyongyang and flew for about 1,000km (621 miles) before falling into waters east of North Korea.
Seoul is closely analysing the launch but officials said they believed the launch was an early test and that developing the Hwasong-18 properly “would need additional time and effort”.
The missile is probably “be some way from credible deployment in any meaningful numbers”, said Joseph Dempsey, a defence researcher at the International Institute for Strategic Studies.
North Korea has fired about 30 missiles this year alone across 12 different launch events.
Kim has also ordered his military to intensify drills to prepare for a “real war“.
Here are some characteristics of solid-fuel technology, and how it can help the North improve its missile systems.
WHAT IS SOLID-FUEL TECHNOLOGY?
Solid propellants are a mixture of fuel and oxidiser.
Metallic powders such as aluminium often serve as the fuel, and ammonium perchlorate, which is the salt of perchloric acid and ammonia, is the most common oxidiser.
The fuel and oxidiser are bound together by a hard rubbery material and packed into a metal casing.
When solid propellant burns, oxygen from the ammonium perchlorate combines with aluminium to generate enormous amounts of energy and temperatures of more than 5,000 degrees Fahrenheit (2,760 degrees Celsius), creating thrust and lifting the missile from the launch pad.
WHO HAS THAT TECHNOLOGY?
Solid fuel dates back to fireworks developed by the Chinese centuries ago, but made dramatic progress in the mid-20th century, when the U.S. developed more powerful propellants.
The Soviet Union fielded its first solid-fuel ICBM, the RT-2, in the early 1970s, followed by France's development of its S3, also known as SSBS, a medium-range ballistic missile.
China started testing solid-fuel ICBMs in the late 1990s.
South Korea said on Friday it had already secured "efficient and advanced" solid-propellant ballistic missile technology.
SOLID VS. LIQUID
Liquid propellants provide greater propulsive thrust and power, but require more complex technology and extra weight.
Solid fuel is dense and burns quite quickly, generating thrust over a short time. Solid fuel can remain in storage for an extended period without degrading or breaking down - a common issue with liquid fuel.
Vann Van Diepen, a former U.S. government weapons expert who now works with the 38 North project, said solid-fuel missiles are easier and safer to operate, and require less logistical support, making them harder to detect and more survivable than liquid-fuel weapons.
Ankit Panda, a senior fellow at the U.S.-based Carnegie Endowment for International Peace, said any country that operates large scale, missile-based nuclear forces would seek solid-propellant missiles, which do not need to be fuelled immediately ahead of launch.
"These capabilities are much more responsive in a time of crisis," Panda said.
WHAT NEXT?
North Korea said the development of its new solid-fuel ICBM, the Hwasong-18, would "radically promote" its nuclear counterattack capability.
South Korea's defence ministry sought to downplay the testing, saying the North would need "extra time and effort" to master the technology.
Panda said the North could face difficulties ensuring such a large missile does not break apart when the diameter of the booster becomes larger.
Although the Hwasong-18 might not be a "game changer", he said, it will most likely complicate the calculations of the United States and its allies during a conflict.
"The most important interest the United States and its allies have is to reduce the risks of nuclear use and escalation stemming from North Korea's possession of these weapons," Panda said.