In a joint declaration this week, NATO leaders condemned North Korea for "fuelling Russia's war of aggression against Ukraine", by "providing direct military support" to Moscow.

NATO leaders also voiced "profound concern" over China's industrial support to Russia.

Pyongyang has repeatedly denied allegations that it is shipping weapons to Moscow, but in June leader Kim Jong Un and Russia's President Vladimir Putin signed an agreement that included a pledge to come to each other's military aid if attacked.

Pyongyang's Korean Central News Agency reported Saturday that the foreign ministry "most strongly denounces and rejects" the NATO declaration.

Citing a ministry spokesman, the agency said the declaration "incites new Cold War and military confrontation on a global scale", and requires "a new force and mode of counteraction".

On the sidelines of the NATO summit, Seoul and Washington this week also signed guidelines on an integrated system of deterrence for the Korean peninsula to counter North Korea's nuclear and military threats.

South Korea's presidential office said Seoul and Washington will carry out joint military drills to help implement the newly announced guidelines, which formalise the deployment of US nuclear assets on and around the Korean peninsula to deter and respond to potential nuclear attacks by Pyongyang.

Relations between the two Koreas are at one of their lowest points in years, with Pyongyang ramping up weapons testing as it draws closer to Russia.

After Pyongyang sent multiple barrages of trash-carrying balloons across the border, Seoul last month fully suspended a tension-reducing military deal and resumed live-fire drills on border islands and by the demilitarised zone that divides the Korean peninsula.