Russia has faced a crucial test of support as the 193 members of the UN General Assembly held an extraordinary debate on a resolution condemning Moscow's "aggression" in Ukraine.
During the rare emergency special session, the 11th the Assembly has held in the United Nations' 77-year history, Russia defended its decision to invade its neighbour as member state after member state made a plea for peace.
"The fighting in Ukraine must stop," warned UN Secretary-General Antonio Guterres, after the session began with a minute of silence for the victims of the conflict.
"Enough is enough. Soldiers need to move back to their barracks. Leaders need to move to peace. Civilians must be protected," he said.
Representatives of more than 100 countries were expected to speak as the global body decides if it will support the resolution that demands Russia immediately withdraws its troops from Ukraine.
The resolution is non-binding but will serve as marker of how isolated Russia is.
The wording of the resolution was watered down to try to attract maximum support, according to drafts seen by AFP. It no longer "condemns" in the strongest terms, Russia's aggression but rather "deplores" it.
A vote is expected on Wednesday. Its authors hope they may exceed 100 votes in favour, though countries including Syria, China, Cuba and India are expected to either support Russia or abstain.
It will be seen as a barometer of democracy in a world where autocratic sentiment has been on the rise, diplomats said, pointing to such regimes in Myanmar, Sudan, Mali, Burkina Faso, Venezuela, Nicaragua and, of course, Russia.
"If Ukraine does not survive, the United Nations will not survive. Have no illusions," said Ukraine's ambassador to the UN, Sergiy Kyslytsya, imploring countries to support the resolution.
Russian ambassador Vassily Nebenzia reiterated Moscow's stance, flatly rejected by Kyiv and its Western allies, that its military operation was launched to protect residents of breakaway regions in eastern Ukraine.
"The hostilities were unleashed by Ukraine against its own residents," he said from the podium.
"Russia is seeking to end this war," Mr Nebenzia added.
2014 Crimea vote
Russian President Vladimir Putin launched the full-scale invasion of Ukraine on February 24.
Moscow has pleaded "self-defence" under Article 51 of the UN Charter.
But that has been roundly rejected by Western countries and the UN, which accuse Moscow of violating Article 2 of the Charter, requiring its members to refrain from the threat or use of force to resolve a crisis.
Addressing the General Assembly, British ambassador Barbara Woodward said countries "must stand together to defend the rules and enforce the accountability that we have built together."
"If we do not stand up for them now, then the safety of every nation's borders and independence are at risk," she said.
China's ambassador, Zhang Jun, said "nothing can be gained from starting off a new Cold War," but did not indicate how Beijing would vote.
The move to hold the emergency session was sparked by Russia using its veto Friday to block a Security Council resolution that condemned Moscow's invasion and called for the immediate withdrawal of its troops.
Russia did not have veto power to derail the referral of the war to the General Assembly, allowed under a 1950 resolution called "Uniting for Peace."
It allows for members of the Security Council to turn to the General Assembly for a special session if the five permanent members, Russia, the United States, Britain, France and China, fail to agree to act together to maintain peace.
There is no right of veto at the General Assembly, which held a similar vote in 2014 condemning Russia's seizure of Crimea and obtained 100 votes in support.
Separately on Monday, the Security Council was scheduled to hold an emergency meeting on the humanitarian situation in Ukraine, where up to seven million people are expected to flee the fighting.
