According to state news agency KCNA, North Korean leader Kim Jong Un oversaw two days of drills "simulating a nuclear counterattack," including the launch of a ballistic missile carrying a dummy nuclear warhead, as South Korea and the United States maintained their military exercises.

Kim expressed "pleasure" over the weekend launches, which KCNA reported was conducted to "familiarize key units with the procedures and processes for performing their tactical nuclear assault missions."

The agency disseminated photographs of Kim at the test, again with his small daughter, as flames erupted from the flying missile before impact. During the exercises, according to the report, a ballistic missile carrying a dummy nuclear warhead flew 800 kilometres (497 miles) before striking a target at an altitude of 800 meters (2,625 feet).

Kim was quoted as saying, using the acronym for his country's official name, the Democratic People's Republic of Korea, "The nuclear force of the DPRK will strongly deter, control, and manage the enemy's reckless moves and provocations with its high war readiness, and will carry out its vital mission without hesitation in the event of any unwelcome situation."

The exercises were Pyongyang's fourth show of force in a week. They occurred as South Korea and the United States conducted their military exercises, known as Freedom Shield, which Pyongyang views as a rehearsal for an invasion and hostile act.

On Sunday, the two allies conducted air and sea drills with American B-1B strategic bombers. On Monday, their navies and marine corps will begin the extensive Ssangyong amphibious landing exercises. The drills, the largest in five years, will last until April 3 for two weeks.

Last month, the United States and South Korea conducted tabletop exercises simulating a nuclear attack by North Korea in response to South Korean President Yoon Suk Yeol's call for greater confidence in US extended deterrence — its military capability, especially atomic forces, to deter attacks on its allies.

Professor Lim Eul-Chul of Kyungnam University's Center of Far Eastern Studies told the AFP news agency that this transforms the Korean peninsula into "a flashpoint with greater potential for nuclear war."

"As the intensity of the South Korea-US drills increases, the likelihood of unanticipated scenarios increases, and as a result, physical conflicts between the two countries may occur," he warned.

In response to North Korea's weapons tests, South Korea and Japan have likewise pushed to strengthen security cooperation, setting aside decades of historical animosity.

UN sanctions imposed in response to North Korea's nuclear weapons development prohibit it from testing ballistic rockets.

The Hwasong-17, North Korea's largest and most powerful intercontinental ballistic missile (ICBM), was launched by Pyongyang for the second time this year last week.

With the request of the United States and Japan, the UN Security Council is scheduled to conduct an emergency meeting on Monday regarding the ICBM launch, according to the Yonhap news agency in South Korea.