North Korean leader Kim Jong-un has promised to "hold hands" with Russian President Vladimir Putin and enhance strategic cooperation for the sake of a common goal: building a powerful country.

Kim committed to this in a message to Putin on the occasion of Russia Day, justifying his decision to invade Ukraine and showing "full support and solidarity".

"Justice is sure to win and the Russian people will continue to add glory to the history of victory," Reuters cites North Korea's state-run KCNA news agency.

He called for "closer strategic cooperation" with Moscow, "holding hands firmly with the Russian president, in conformity with the common desire of the peoples of the two countries to fulfil the grand goal of building a powerful country".

North Korea has sought closer ties with the Kremlin and supported Moscow after it invaded Ukraine last year, blaming it for the "hegemonic policies" and "high-handedness" of the US and the West.

On 31 May, the DPRK attempted to launch a device Pyongyang calls a military intelligence satellite. The launch failed, with the satellite falling into the Yellow Sea.

Although Pyongyang has said it plans to repeat the launch as soon as possible, experts believe that it will take months for the DPRK to sort out the technical defects that manifested themselves during the launch.