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”.