Vladimir Putin has been blasted as a "pathetic old man" by a Ukrainian MP, while Taoiseach Micheál Martin has also hit out at the Kremlin leader.
In an address to the nation on Wednesday morning, Mr Putin threatened a nuclear attack on the West, saying that there had been "nuclear blackmail" against Russia and that Russian reservists will be conscripted into Russia's military from Wednesday in what is Russia's first mobilisation since World War Two.
His actions are seen to be slightly desperate given how the illegal invasion of Ukraine, which began in March, has gone - with Ukraine gaining a number of territories back during a counter-attack earlier this month.
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Speaking on Wednesday morning from his office, Mr Putin said: "The West has engaged in nuclear blackmail against us. If its territorial integrity is threatened, Russia will use all the means at its disposal to protect our people. This is not a bluff."
However, speaking to RTÉ's Morning Ireland in the aftermath of the declaration, Ukrainian MP Inna Sovsun said this was the action of a "pathetic old man".
"He is desperate in the war he got stuck in. Are we scared, yes we are," she noted.
"But Putin has also shown today that he is scared".
Meanwhile, Taoiseach Micheál Martin was asked by reporters at the National Ploughing Championships for his reaction to Mr Putin's address.
He responded: "This is a needless killing of young people, and now more young people are going to be mobilised in Russia. And for what? For a 19th century imperialist objective which simply cannot and will not be realised."
Mr Martin will travel to New York later on Wednesday to attend a United Nations General Assembly, where President of Ukraine Volodymyr Zelenskyy and US President Joe Biden are set to speak on the illegal invasion.
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