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UN Secretary General Antonio Guterres on Monday made an impassioned plea for Russia to halt its military attack on Ukraine at an emergency meeting aimed at further isolating Moscow on the world stage.
Mr Guterres said Russian missiles and air strikes were “pounding Ukrainian cities day and night”, that the capital city Kiev was “encircled and under attack from all sides” and that the large-scale assault “must stop now”.
The UN chief also called Russian President Vladimir Putin’s decision on Sunday to put Russia’s nuclear forces on high alert a “chilling development”. The move has also been condemned by the US and others.
“The mere idea of a nuclear conflict is simply inconceivable. Nothing can justify the use of nuclear weapons,” Mr Guterres told a rare emergency special session of the UN's 193-member General Assembly to discuss whether to condemn Russia’s “unprovoked armed aggression” in Ukraine and demand its immediate withdrawal.
“In the face of the continuing Russian attacks, Kiev’s three million residents are being forced to seek safety in their homes, improvised bomb shelters and in the city’s subways," said Mr Guterres.
“Although Russian strikes are reportedly largely targeting Ukrainian military facilities, we have credible accounts of residential buildings, critical civilian infrastructure and other non-military targets sustaining heavy damage.”
All UN member states have a chance to speak at the debate and to cast votes — making the event a barometer of global attitudes towards the situation in Ukraine and the worst fighting Europe has seen in years.
It is only the 11th time in the UN's history that such an emergency session has been held. It began with diplomats standing for one minute in silence to honour the victims of fighting in Ukraine before assembly president Abdulla Shahid spoke, calling for "an immediate ceasefire".
The US and others backing the document hope to get more than 100 votes in favour — though countries including Syria, Venezuela, China, Cuba and India are expected to either support Russia or abstain.
Ukraine's UN ambassador Sergiy Kyslytsya said Mr Putin's "madness" was a threat to global security on par with the events preceding the Second World War.
"Today, the Russian army shelled with multiple rocket launcher systems the residential areas of the city of Kharkiv, the second biggest in Ukraine," said Mr Kyslytsya.
"Innocent civilians have been killed and wounded. The exact numbers, it's very difficult to estimate because so far, the warfare [continued] while the negotiations [were] still under way at the border with Belarus."
Russia's UN envoy Vassily Nebenzia blamed Ukraine for the war and for unleashing violence "against its own residents" in the breakaway pro-Moscow eastern regions.
Moscow wants "to end this war", added Mr Nebenzia.
Later, Mr Nebenzia told reporters that Russia was "not isolated" and complained that the US had expelled a dozen Russian diplomats from the country's mission to the UN in New York.
Given the lengthy list of speakers, the debate and voting could take more than a day.
The meeting was the latest in a flurry of diplomacy at the UN. Russia on Friday vetoed a draft Security Council resolution that would have condemned Moscow's invasion of Ukraine.
China, the UAE and India abstained and the remaining 11 members voted yes.
Later on Monday, the Security Council is set to hold emergency talks on the unfolding humanitarian crisis in Ukraine, where as many as seven million people are expected to flee the fighting.
Mr Putin on February 24 launched a large-scale military assault into neighbouring Ukraine, deploying tens of thousands of troops in and around the country, equipped with tanks, fighter jets and ships.
Russia has since become a global pariah as ordinary Ukrainians take up arms to defend their country. Moscow has been hit by wide-ranging sanctions including a ban from western airspace and key financial networks.