North Korean leader Kim Jong Un threatened to use nuclear weapons to destroy South Korea if attacked, state media reported Friday, after South Korea’s president warned that if the North used nuclear weapons it would “face the end of its regime.”

The fiery rhetoric isn’t new, but comes at a time of tension on the Korean Peninsula and just weeks after North Korean state media released images of Kim visiting a uranium enrichment facility, which produces weapons-grade nuclear materials.

While touring an army base in the western part of the country Wednesday, Kim said if the South were to encroach upon the North’s sovereignty, Pyongyang “would use without hesitation all the offensive forces it has possessed, including nuclear weapons,” the state-run Korean Central News Agency reported Friday.

“If such situation comes, the permanent existence of Seoul and the Republic of Korea would be impossible,” Kim added, using the proper name for South Korea.

Hostilities between the two Korean leaders have been simmering this year as North Korea has appeared to have intensified its nuclear production efforts and strengthened ties with Russia, deepening widespread concern in the West over the isolated nation’s direction.

Kim’s comments appeared to come in direct response to South Korean President Yoon Suk Yeol, who on Tuesday showcased Seoul’s most powerful ballistic missile and other weapons designed to deter North Korean threats during a parade for Armed Forces Day.

North and South Korea have been cut off from each other since the end of the Korean War in 1953, which concluded with an armistice not a peace treaty, leaving the two sides still technically at war.

While both governments had long sought the goal of one day peacefully reunifying, earlier this year Kim announced the North would no longer pursue that aim, calling the South the “principal enemy” and demolishing a monument symbolizing unification.

Last month, North Korean state media released photos of Kim purportedly touring a nuclear facility in a rare glimpse of the nation’s closely guarded weapons program. Experts said the images – which show Kim flanked by men in military uniforms and crisp white lab shirts – underscore North Korea’s growing confidence in its position as a nuclear power.

South Korea has also been building up its arsenal to respond to a potential threat from the North.

On Tuesday, Yoon unveiled the Hyunmoo-5 ballistic missile, which is reportedly capable of penetrating North Korean underground bunkers.

“If North Korea attempts to use nuclear weapons, it will face the resolute and overwhelming response of our military and the SK-US alliance,” Yoon said, in reference to the United States as the country’s key military partner. “The North Korean regime must now break free from the delusion that nuclear weapons will protect them.”

The US flew a B-1B bomber over an Armed Forces Day ceremony on Tuesday in Seongnam, near Seoul, in an apparent show of solidarity.

On Wednesday, Kim called Yoon a “puppet” and said he was an “abnormal man” for bragging about his military might at the doorstep of a nation in possession of nuclear weapons, KCNA reported.

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