Russian Defence Minister Andrei Belousov met with North Korean leader Kim Jong Un and agreed to boost military cooperation between the two isolated nations, Pyongyang state media said on Saturday.

The United States and South Korea have accused the nuclear-armed North of sending more than 10,000 soldiers to help Russia fight Ukraine, with experts saying Kim is eager to gain advanced technology, and battle experience for his troops, in return.

Kim, who met Belousov on Friday, blasted the recent decision by Western powers to permit Kyiv to strike inside Russia with their weapons, saying it constituted a “direct military intervention in the conflict”, according to KCNA.

“It is an exercise of the right to self-defence for Russia to take resolute action to make the hostile forces pay the price,” Kim was quoted as saying.

Russian President Vladimir Putin and Kim signed a strategic partnership treaty in June that obligates both states to provide military assistance “without delay” in the case of an attack on the other and jointly oppose Western sanctions.

KCNA said on Saturday that Belousov’s visit “would greatly contribute to bolstering up the defence capabilities of the two countries and… promoting the friendly, mutual cooperation and development of the relations between the two armies.” Belousov, in a statement, expressed gratitude for the two countries’ deeping bonds and praised North Korea’s “absolutely independent foreign policy”.

North Korean leader Kim Jong Un said his country would use nuclear weapons “without hesitation” if attacked by the South and ally the United States, state media reported on Friday.

Relations between the two Koreas are at one of their lowest points in decades, with Seoul this week staging a military parade where it showcased its bunker-busting “monster” missile and President Yoon Suk Yeol warned Kim that using nukes would mean the end of his regime.

Pyongyang has also been bombarding the South with balloons carrying bags of trash, and a fresh flurry was seen floating over Seoul early on Friday by AFP reporters. Seoul’s military confirmed it had detected the balloon launches overnight.

If an enemy’s forces were “encroaching upon the sovereignty” of the North, Pyongyang would “use without hesitation all the offensive forces it has possessed, including nuclear weapons,” Kim said, according to the official Korean Central News Agency.

Images in state media showed Kim, clad in his customary leather jacket, speaking at a training event for special operations forces.

There, he slammed Yoon for his “end of regime” comments and “clamouring” about his country’s alliance with the United States.

Seoul, which does not have nuclear weapons of its own, is covered by the US nuclear umbrella, and Washington has stationed tens of thousands of troops in the country since the Korean War ended in 1953 without a peace treaty.

Kim said it was Seoul and Washington who were “destroying regional security and peace”, KCNA reported, while branding South Korea’s leader “an abnormal man”.

Military parade

On Tuesday, fighter jets flew over downtown Seoul and tanks rolled through the streets, as South Korea displayed for the first time its largest ballistic missile, the Hyunmoo-5, which is capable of destroying underground bunkers.

An American B-1B heavy bomber also staged a flyover of the ceremony early Tuesday, flanked by F-15K jets.

Washington periodically deploys nuclear assets to the Korean peninsula, underscoring its protection of the South from Pyongyang’s growing threats.

At the event marking South Korea’s Armed Forces Day, Yoon said that if the North “attempts to use nuclear weapons, it will face the resolute and overwhelming response of our military and the US and Republic of Korea alliance.”

“That day will be the end of the North Korean regime,” he added.

North Korea is expected to to scrap a landmark inter-Korean agreement signed in 1991 at a parliamentary meeting next week, Seoul’s unification ministry said Wednesday, as part of Kim’s drive to officially define the South as an enemy state.

Earlier this year, Kim called to remove unification-related clauses from the constitution, while abolishing agencies dedicated to improving ties with the South.

Last month, the North also disclosed images of a uranium enrichment facility for the first time, showing leader Kim touring the site as he called for more centrifuges to boost the country’s nuclear arsenal.

South Korea’s spy agency later said the unprecedented disclosure was “directed at the US” and that North Korea was believed capable of producing a double-digit number of nuclear weapons.

Last week, a lawmaker told reporters that the National Intelligence Service had warned the North might carry out another nuclear test — its seventh — after the US elections in November.