North Korea said on Friday it had tested a new solid-fuel intercontinental ballistic missile (ICBM), the Hwasong-18, to “radically promote” its nuclear counterattack capability, state media said.

Leader Kim Jong Un guided the test, and warned it would make 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”.

North Korea has criticised recent U.S.-South Korean joint military exercises as escalating tensions, and has stepped up weapons tests in the past months.

South Korea’s defence ministry said North Korea was still developing the weapon, and that it needed more time and effort to master the technology, indicating that Pyongyang might carry out more tests.

North Korean state media outlet KCNA released photos of Kim watching the launch, accompanied by his wife, sister and daughter, and the missile covered in camouflage nets on a mobile launcher. A state media video showed the missile blasting off from a launch tube, creating a cloud of smoke.

“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 its official name.

“Pho” means “artillery” in Korean.

Analysts said it is the North’s first use of solid propellants in an intermediate-range or intercontinental ballistic missile.

Developing a solid-fuel ICBM has long been seen as a key goal for North Korea, as it could help the North deploy missiles faster during a war.