On Monday, official media KCNA said that Kim Jong Un had overseen drills simulating a nuclear retaliation against the U.S. and South Korea as a warning to the allies.

The North launched a short-range missile from a subterranean silo, which analysts think might enhance intercontinental ballistic missile testing (ICBM).

KCNA accused Washington and Seoul of “explicitly attempting to launch a war” against it and said the Saturday and Sunday drills will enhance “war deterrent and nuclear counterattack capacity.”

“The practice also meant to display our harder will to make a genuine war reaction and convey a stronger warning to the enemy who increase their war rehearsals for aggression,” KCNA reported.

KCNA said a ballistic missile with a dummy nuclear payload traveled 800 km (497 miles) before hitting a target in tactical nuclear assault drills.

KCNA images showed Kim again attending the test with his young daughter as the missile blasted before hitting the target.

The photographs showed a KN-23 short-range ballistic missile (SRBM) launch. Still, unlike previous tests, the engine exhaust seemed to be vented on either side after liftoff, suggesting a silo was employed.

“Until recently, North Korea has favoured mobile launchers for everything from SRBMs to even massive ICBMs,” said Yang Uk, a fellow at the Asan Institute for Policy Research in Seoul. “The latest launch may test bigger missiles like the Hwasong-17 ICBM in a silo.”

South Korea’s defense ministry spokesperson claimed the North is making substantial technological progress in its nuclear program but did not explain.

Kim claimed the exercises boosted the military’s fighting capacity and ordered it to prepare for an “immediate and overwhelming nuclear response anytime.”

“The present scenario, in which the enemies are become ever more evident in their attempts for aggression against the DPRK, urgently necessitates the DPRK to strengthen up its nuclear war deterrence exponentially,” KCNA cited him.

Kim used the abbreviation of his country’s official name, the Democratic People’s Republic of Korea.

“The DPRK nuclear force will resolutely deter, control, and manage the enemy’s reckless acts and provocations with its high combat preparedness, and carry out its crucial job without hesitation in any undesired circumstance,” he said.

On Sunday, South Korea and Japan reported a North Korean short-range ballistic missile launch off the east coast.

North Korea has denounced South Korea-U.S. military drills as an invasion rehearsal.

U.S. B-1B bombers participated in allied air and sea training on Sunday.

The U.S. and South Korean fleets and marine corps will begin their first large-scale Ssangyong amphibious landing drills in five years on Monday for two weeks until April 3.

South Korean President Yoon Suk Yeol encouraged to trust in U.S. extended deterrence, notably nuclear capabilities, by staging tabletop drills mimicking North Korea’s nuclear assault last month.

KCNA said more than 1.4 million North Koreans have volunteered to battle Seoul and Washington, up from 800,000 two days before.