Moscow, Russia - Russian senators on Wednesday unanimously ratified a mutual defense pact with North Korea, formalizing months of deepening security cooperation between the two nations.

Having become one of Russia's most staunch and important backers in its military campaign against Ukraine, Pyongyang first signed the strategic partnership with Moscow in June. It commits both countries to come at each other's defense in case of any aggression.

Kremlin official Andrei Rudenko called North Korea the "only country in the world to publicly support" both Russia's annexation of Crimea and its ongoing invasion of Ukraine.

About 10,000 North Korean troops have reportedly been deployed to Russia as a way to bolster Moscow's war. North Korea has also faced accusations of supplying artillery shells and missiles used against Ukraine.

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The ratification of the defense agreement comes the day after a majority of UN Security Council Members publicly urged Pyongyang to give up its ballistic missile arsenal.

"We call on the DPRK to return to negotiations, comply with its obligations under numerous UN Security Council resolutions, and abandon its weapons of mass destruction and ballistic missile programs," council members said in a joint statement read out by deputy US ambassador Robert Wood.

On Tuesday, Ukrainian president Volodymyr Zelensky issued a statement on X in which he thanked the international response to North Korean soldiers arriving in Russia.

"The first battles with North Korean soldiers mark a new chapter of global instability. Together with the world, we must do everything to ensure that this Russian step toward expanding the war – this true escalation – becomes a loss. A loss for Russia and North Korea alike," Zelensky said.