On Sunday night, the US national security advisor, Jack Sullivan claimed that America has “communicated directly, privately to the Russians at very high levels” about how the country would respond if Vladimir Putin acted on his nuclear threats.
Speaking with NBC’s Meet the Press programme, Mr Sullivan said: “If Russia crosses this line, there will be catastrophic consequences for Russia.
“The United States will respond decisively.”
The national security advisor did not go into detail about what had been discussed or what the planned response was, but Mr Sullivan said the US had spelt out in “greater detail exactly what that would mean” to Russian officials.
In an address to Russia last week, President Vladimir Putin said that Moscow owned “various weapons of destruction” and would “use all the means available to us”, before adding: “I’m not bluffing.”
In a separate interview on Sunday, Mr Sullivan said that Putin’s threats were a “matter that we have to take deadly seriously”.
According to the Telegraph, military analysts have warned that Putin could use Russia’s military doctrine, which allows it to use nuclear weapons to defend Russian territory, to seem like the defending party during the war in Ukraine.
This weekend, Russian Foreign Minister Sergei Lavrov addressed the United Nations General Assembly and was asked if Russia would have grounds to use nuclear weapons to defend annexed regions of Ukraine.
He said that Russia would use “all of the laws, doctrines, concepts and strategies of the Russian Federation apply to all of its territory”.
The Foreign Minister also claimed that the regions of Ukraine currently under Russian military occupation are “suffering from the abuses of the neo-Nazi regime”.
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On Friday, September 23, Russia began a referendum in four Ukraine regions currently under military occupation if they should join Russia.
The voting is currently taking place in Luhansk and Kherson, which Russia has full control over, plus Donetsk and Zaporizhzhia, which Ukraine has about 40 percent control over.
The results of the referendum would mean Ukraine would lose 15 percent of its land and could risk direct military confrontation with both the Russian and NATO military.
The referendum is similar to the 2014 annexation of Crimea, which was condemned internationally at the time for violating Ukraine’s constitution and breaking international law as the voting was held under military occupation.
World leaders have condemned the current referendum, with Mr Sullivan saying that the United States would “never recognise” Russia’s annexation of Ukraine’s land.
The national security advisor said: “Russia is throwing together sham referendums on three days’ notice, as they continue to lose ground on the battlefield and as more world leaders distance themselves from Russia on the public stage, and Russia is scraping for personnel to throw into this fight.”
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It has been reported that since the referendum began, Russian soldiers have been going to households in occupied regions to hand out ballots and find voters.
In the city of Melitopol, only one in five residents have voted in the referendum, and Ukraine’s elected mayor of Melitopol, Ivan Fedorov said: “Our citizens haven’t taken part in this fake referendum.”
He added: “After three days Russia has only been able to find just 20 per cent of people to vote. Nobody wants to vote, nobody wants to say yes to the Russian referendum.”
“Ninety percent” of those forced to vote have voted against becoming part of Russia, according to the mayor.
Mr Fedorov also claimed Russia has introduced the rouble as a regional currency and issued Russian passports to residents, as well as blocked residents from evacuating into Ukraine-controlled territories.
He said: “The city’s been fully occupied for the last seven months. Many thousands of citizens stay in Melitopol … and we can’t give them support or safety guarantees.”