North Korea tests solid fuel missile. What is it and why it is more powerful than liquid missile?

North Korea on Friday boasted that it had flight-tested a solid-fuel intercontinental ballistic missile (ICBM) for the first time — possibly meaning progress in the regime's efforts to target the continental United States.

North Korean leader Kim Jong Un said the missile — named Hwasong-18 — was the most devastating weapon in his nuclear forces.

What do we know about the launch?

North Korea's official Korean Central News Agency (KCNA) released photos of Kim watching the launch alongside his wife, sister, and daughter.

The missile was covered in camouflage nets on a mobile launcher ahead of the countdown.

KCNA issued its statement a day after the country's neighbors detected a long-range missile launch near the capital, Pyongyang.

"The development of the new-type ICBM Hwasongpho-18 will extensively reform the strategic deterrence components of the DPRK, radically promote the effectiveness of its nuclear counterattack posture and bring about a change in the practicality of its offensive military strategy," KCNA said, using the initials of the country's official name.

Leader Kim Jong Un has described Hwasong-18 as the most powerful weapon in his nuclear arsenal. Kim had previously criticized recent US-South Korean joint military exercises and urged a "more practical and offensive" way to deter North Korea's perceived enemies.

He warned that the tests would make North Korea's enemies "experience a clearer security crisis, and constantly strike extreme uneasiness and horror into them by taking fatal and offensive counter-actions until they abandon their senseless thinking and reckless acts."

The Japanese government on Thursday warned people on the northernmost main island of Hokkaido to "evacuate immediately" and seek shelter in a building or underground. Later, the evacuation alert was lifted when the missile crashed into the sea.

Pyongyang has fired more than 100 missiles into the sea since the start of 2022. North Korea's leader has said he also wants his country to ramp up the production of "weapon-grade nuclear material" to make more bombs.

What's so important about solid fuel missiles?

Solid-fuel missiles are easier to store and transport, more stable, and easier to prepare for launch — making them harder to detect and destroy pre-emptively.

Liquid missiles must be filled with fuel and an oxidiser a short time before they are fired. Solid fuel projectiles, however, rely on a system more similar to a portable battery that can easily be inserted or unplugged.

How advanced is North Korea's missile program?

The South Korean Defense Ministry has described the Hwasong-18's flight as a "mid-phase test," adding that North Korea would need more time and effort to complete the system.

Seoul maintains that the North's technologies are still not developed enough to protect its (ICBM) warheads from the harsh conditions of reentry into the atmosphere.

It also added that the country did not yet have the technology to put nuclear warheads on shorter-range missiles to use on the Korean Peninsula.

Ankit Panda, an expert with the Carnegie Endowment for International Peace said the latest test was a "significant breakthrough for the North Koreans, but not an unexpected one."

"The primary significance of solid-fuel ICBMs is in terms of what they'll do for the survivability of North Korea's overall ICBM force," he said.

"Because these missiles are fueled 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."