Russian President Vladimir Putin has ordered for military deterrence forces - which include nuclear weapons - to be put on "special alert", BBC reports.
In a statement to defense chiefs on Sunday, Putin explained that the measures were being taken because of "aggressive statements" and "unfriendly measures" from Western nations who had condemned his invasion of Ukraine.
In a translation by The Guardian, Putin said: "as you can see, not only do Western countries continue to take unfriendly measures against our country in the economic dimension - I mean the illegal sanctions that everyone knows about very well - but also the top officials of leading NATO countries to make aggressive statements with regards to our country."
He went on to add: "That is why I order defence minister and chief of the general staff to put Russian army deterrence forces on high combat alert."
The announcement constitutes a considerable threat by Putin to use any measures possible to continue his campaign in Ukraine unhindered. It was immediately condemned by the US, who called it an "unacceptable escalation" per BBC.
Putin seemed to allude to his nuclear capabilities last week when he warned that "whoever tries to hinder" his troops in Ukraine would face consequences "you have never seen in your history."
Despite his threat, Russia has been widely condemned by the global community. A rare emergency session of the UN was called to discuss Ukraine despite Putin's attempts to stop it.
Meanwhile, the EU, Turkey, and Sweeden are just some of the countries that have placed sanctions on Russia and sent aid to the invaded Ukraine.
NATO secretary general Jens Stoltenberg told CNN that Putin's latest threat is "dangerous rhetoric" and "behavior which is irresponsible."
The US ambassador to the United Nations Linda Thomas-Greenfield also reacted to the move during an appearance on CBS.
"President Putin is continuing to escalate this war in a manner that is totally unacceptable and we have to continue to condemn his actions in the strongest possible way," she said.