Kim Jong Un said his forces would use nuclear weapons “without hesitation” if Pyongyang’s territory were attacked by the South and its ally, the United States. His remarks came a day after the North tested its latest intercontinental ballistic missile (ICBM) in a move that further escalated tensions with Seoul and Washington.

During a meeting with military commanders, Kim said it is imperative to sharpen “the treasured sword” that safeguards national security. He was referring to the nuclear weapons that North Korea has cultivated for decades despite international sanctions.

The leader warned the enemy of the “overwhelming counteraction of the DPRK’s powerful military force,” KCNA news agency quoted him. The DPRK is short for the Democratic People’s Republic of Korea, the country’s official name. Kim said the DPRK’s military strength has reached the highest level and is “ready for any attack by its enemies.”

Last year, Kim adopted a policy of not hesitating to use nuclear weapons first if provoked. Since then, the North has conducted a series of missile and nuclear tests. Experts say the country has a stockpile of enough fissile material to produce dozens of nuclear bombs.

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Relations between the two Koreas have been tense for months as Pyongyang continues to test nuclear-capable ballistic missiles. It has already conducted more than 100 missile tests this year despite international pressure to end the tests. North Korean officials have also sought to improve its ties with China and Russia, which have blocked efforts by the U.S. and South Korea to tighten North Korea-related international sanctions.

Pyongyang is also believed to be increasing the production of its military-related equipment, including satellites and attack drones, to strengthen its deterrent against outside forces. The South, which has no nuclear weapons of its own, recently resumed anti-Pyongyang propaganda broadcasts near the border after catching Pyongyang sending thousands of balloons carrying trash into the region.

The South also showcased its bunker-busting “monster” missile during this week’s annual military parade in which it honored its troops. This prompted the North to fire off a barrage of verbal attacks against its longtime ally. The North referred to South Korean President Yoon Suk Yeol as a confrontation maniac and said he should know that the North’s nuclear weapons would bring about his downfall. Yoon has vowed to continue using conventional arms to counter the North’s nuclear weapons.