The U.S. warned on Wednesday that Russia appears close to accepting North Korea as a nuclear weapons state amid deepening military cooperation between the allies, despite previously voting to sanction Pyongyang over its nuclear development.

“Alarmingly, we assess that Russia may be close to accepting North Korea’s nuclear weapons program, reversing Moscow’s decades-long commitment to denuclearize the Korean Peninsula,” U.S. Ambassador Linda Thomas-Greenfield said during a U.N. Security Council (UNSC) meeting to discuss DPRK support for Russia’s invasion of Ukraine.