In a dramatic escalation of East-West tensions over Russia's invasion of Ukraine, President Vladimir Putin ordered Russian nuclear forces put on high alert Sunday in response to what he called "aggressive statements" by leading NATO powers.
The order means Putin has ordered Russia's nuclear weapons prepared for increased readiness to launch, raising the threat that the tensions could boil over into nuclear warfare. In giving it, the Russian leader also cited hard-hitting financial sanctions imposed by the West against Russia, including Putin himself.
Speaking at a meeting with his top officials, Putin directed the Russian defense minister and the chief of the military's General Staff to put the nuclear deterrent forces in a "special regime of combat duty."
"Western countries aren't only taking unfriendly actions against our country in the economic sphere, but top officials from leading NATO members made aggressive statements regarding our country," Putin said in televised comments.
The Russian leader this week threatened to retaliate harshly against any nations that intervened directly in the conflict in Ukraine, and he specifically raised the specter of his country's status as a nuclear power.
The U.S. ambassador to the United Nations responded to the news from Moscow while appearing on a Sunday news program.
"President Putin is continuing to escalate this war in a manner that is totally unacceptable," Ambassador Linda Thomas-Greenfield said. "And we have to continue to condemn his actions in the most strong, strongest possible way."
The alarming step came as street fighting broke out in Ukraine's second-largest city and Russian troops squeezed strategic ports in the country's south, advances that appeared to mark a new phase of Russia's invasion following a wave of attacks on airfields and fuel facilities elsewhere in the country.
Additional reporting by the Associated Press.