North Korean leader Kim Jong Un referred to his country as an "invincible comrade-in-arms" with Russia in a message to President Vladimir Putin, reported state media KCNA on Wednesday. This comes amid speculation about Putin's potential visit to North Korea.

In celebration of Russia's National Day, Kim highlighted that their meeting at a Russian space launch facility last year strengthened their "century-old strategic relationship." This statement follows a report by Russia's Vedomosti newspaper on Monday indicating Putin's upcoming visits to North Korea and Vietnam.

A Vietnamese official told Reuters that Putin's visit to Vietnam is tentatively scheduled for June 19 and 20, though it remains unconfirmed. The Kremlin has expressed a desire to enhance cooperation with North Korea "in all areas" but has not confirmed the visit's date.

Kim visited Russia's Far East last September, including a tour of the Vostochny Cosmodrome space launch center, where Putin promised satellite-building assistance.

Kim praised Russia's achievements in becoming a strong nation, despite facing sanctions and pressures from hostile forces.

In recent months, Pyongyang and Moscow have intensified their diplomatic and security relations, with multiple government and parliamentary delegations visiting each other. A North Korean public security delegation is also set to visit Russia this week.

Meanwhile, officials in Washington and Seoul have accused North Korea of supplying weapons to Russia to support its war in Ukraine, allegedly in exchange for technological assistance with its nuclear and missile programs.