Kim Jong Un warned enemies of “extreme discomfort and horror” afterwards. North Korea said Friday it had tested a new solid-fuel intercontinental ballistic missile, or ICBM, Hwasong-18 “radically promote” its nuclear capability..

What happened: South Korea called Pyongyang fired what appeared to be one new ballistic missile model on Thursdaywhich also struck a chord in northern Japan, where Hokkaido residents were urged to take cover.

“The development of the new Hwasongpho-18 ICBM will comprehensively reform the DPRK’s strategic deterrent components, radically boost the effectiveness of its nuclear counterattack posture and bring about a change in the practicality of its offensive military strategy,” state media reported.

See also: Kim Jong Un calls for readiness for nuclear war in the face of the “reckless movements and provocations of the enemy”.

Leading the test, Kim warned that enemies would “experience a clearer security crisis and continually induce extreme discomfort and terror in them, using deadly and offensive countermeasures until they give up their mindless thinking and reckless actions.”

Why it matters: This was the first time Kim’s isolated nation used solid propellants a medium or intercontinental ballistic missile. The majority of the country’s largest ballistic missiles rely on liquid propellant, which requires loading propellant at the launch site – a process that takes a long time.

“Solids are easier and safer for troops to operate in the field, and have a much smaller logistical train that makes field-deployed solid fuel rocket units harder to detect (and thus more survivable) than liquids,” Vann Van Diepen, a former US Navy weapons expert Government, the expert told Reuters.

Also read: Trump says Kim Jong Un, Queen Elizabeth II, Oprah Winfrey have ‘kissed my a**’ in letters: ‘Now I only have half of them…’