North Korea said Tuesday that its leader Kim Jong-un has overseen the country’s first nuclear drills against a potential attack by an enemy.

The Workers’ Party of Korea-owned daily Rodong Sinmun said the live-fire drills involving “new” and “super large” rocket launchers were held a day prior on Monday under Kim’s guidance.

According to the report, Monday’s drills are the first demonstration of North Korea‘s central nuclear weapons management and control system called “nuclear trigger.” The report said the drills were “a clear warning to our enemies.”

The drills consisted of “practical training to master the process of conducting a nuclear counterattack when the highest level of nuclear crisis alert is declared” and “firing of rocket launchers capable of delivering tactical nuclear warheads.”

The report said Kim was “satisfied with the successful execution of the drills,” which strengthened the country’s capabilities to carry out tactical nuclear attacks and realized the goals of expanding its nuclear portfolio.

The report cited the Korea Flying Training, the two-week South Korea-US air exercises that began on April 12, and other joint training as the main reasons behind the execution of its counterattack drills.

The South Korea and the US combined exercises are “constant military provocations by hostile powers that seek to crush us through force,” the report said.

On Monday, North Korea fired several short-range ballistic missiles toward the sea between the Korean Peninsula and Japan from Pyongyang, according to South Korea’s Joint Chiefs of Staff, just three days after testing its new strategic cruise missile and anti-aircraft missile.