North Korean leader Kim Jong-un (right) and Russian President Vladimir Putin pose for a photo after signing the "Treaty on Comprehensive Strategic Partnership between the Democratic People's Republic of Korea and the Russian Federation" at the Kumsusan State Guest House in Pyongyang on Wednesday. (KCNA)

North Korea on Monday criticized the United States for its military support of Ukraine and supported Russia's actions as a "legitimate act of self-defense," underscoring the growing military ties between Moscow and Pyongyang.

"If the rulers of the US persist in recklessly pushing their war machine into Ukraine for a proxy war against Russia, it will inevitably provoke a stronger response from Russia," Pak Jong Chon, vice chairman of the Central Military Commission of the Workers' Party of Korea, said in a statement carried by the Korean Central News Agency.

Pak further said, "It is Russia's right to self-defense to make a strategic counterattack to defend its security from the ever-aggravating threat posed by hostile forces. Any responsive action taken by Russia will be a legitimate act of self-defense."

Last week, North Korean leader Kim Jong-un expressed "full support" for Russia's war in Ukraine and pledged to strengthen strategic cooperation with Moscow as he held summit talks with Russian President Vladimir Putin in Pyongyang.

"We will always stand together with the Russian army and people in a just struggle to defend sovereign rights, strategic stability, and the territorial integrity of their country," Pak said.

In particular, Pak criticized the US for recently expanding its agreement with Ukraine to strike over the border inside Russian territory wherever Russian forces are engaging in cross-border attacks into Ukraine, not just in the Kharkiv region as was previously signed.

"This time the US has gone so far as to allow the Ukrainian neo-Nazis to strike any part of Russian territory at their will," Pak said. (Yonhap)