The Russian and Ukrainian delegates to the United Nations have addressed an emergency Security Council session held hours after Russian President Vladimir Putin there.
The United States and its allies rounded on Russia during the meeting, calling it a violation of international law and "pretext for war", while the Australian government said the Russian personnel sent into the Ukrainian territories were "not peacekeepers".
Addressing the UN session, US ambassador Linda Thomas-Greenfield also heaped scorn on Mr Putin's assertion the Russian troops would take on a peacekeeping role in the two breakaway regions - the self-proclaimed Donetsk People's Republic and the Lugansk People's Republic.
"He calls them peacekeepers. This is nonsense. We know what they really are," Ms Thomas-Greenfield said.
Tensions between Moscow and Western capitals are high following weeks of accusations Russia deployed up to 150,000 troops near Ukraine's borders for an invasion. Russia has denied it wants to invade Ukraine and accuses the West of hysteria.
Ukraine's borders remain "unchangeable" regardless of Russia's recent actions, Kyiv's ambassador to the UN told the Council.
"The internationally recognised borders of Ukraine have been and will remain unchangeable regardless of any statements and actions by the Russian federation," Sergiy Kyslytsya said.
Moscow is still "open to diplomacy for a diplomatic solution", said Russia's ambassador, Vasily Nebenzya.
"However, allowing a new bloodbath in the Donbass is something we do not intend to do," he added, referring to the region encompassing Donetsk and Lugansk.
Mr Putin's order has been widely seen as paving the way for an operation to deploy part of the potential invasion force he has massed on Ukraine's borders.
In a lengthy televised national address announcing his recognition of the rebel-held areas, Mr Putin railed against Ukraine as a failed state and "puppet" of the West, repeatedly suggesting it was essentially part of Russia.
Ms Thomas-Greenfield said the speech amounted to a "series of outrageous, false claims" that were aimed at "creating a pretext for war".
"President Putin has torn the Minsk Agreement to shreds. We have been clear that we do not believe he will stop at that," she said, referring to the agreements of 2014 and 2015 that aimed to end conflict between the Ukrainian army and Russian-backed separatists in eastern Ukraine.
China's ambassador called for restraint by "all sides" to avoid further escalation.
"All parties concerned must exercise restraint and avoid any action that may fuel tensions. We welcome and encourage every effort for a diplomatic solution," Zhang Jun said.
It is the third Security Council meeting on Ukraine in as many weeks. The body has met dozens of times to discuss the Ukraine crisis since Russia annexed Ukraine's Crimea region in 2014.
It cannot take any action because Russia is a veto-power along with France, Britain, China and the United States.
UN Secretary-General Antonio Guterres believes Russia has violated the territorial integrity and sovereignty of Ukraine with its decision to recognise eastern Ukraine as independent entities, a UN spokesman said.
A 'critical' moment
Russia, which currently holds the rotating presidency of the Council, had wanted the session to be closed but the United States insisted it be public.
The Under Secretary-General for Political and Peacebuilding Affairs, Rosemary DiCarlo, voiced "regret" that Russian troops were ordered to Eastern Ukraine.
"The next hours and days will be critical," Ms DiCarlo said. "The risk of major conflict is real and needs to be prevented at all costs.
Moscow provided no details or date for any deployment of the "peacekeeping" forces, only saying that it "comes into force from the day it was signed".
British envoy Barbara Woodward said the council must be united in urging Russia to "deescalate" and "respect its obligations".
"Russia has brought us to the brink. We urge Russia to step back," Ms Woodward said, as Martin Kimani of Kenya said Russia's move "breaches the territorial integrity of Ukraine".
"Multilateralism lies on its deathbed tonight. It has been assaulted today, as it has been by other powerful states in the recent past," Mr Kimani said.
Australia condemns Russia
As the UN meeting continued, the Australian government condemned Russia's declaration and deployment of troops.
In a statement on Tuesday afternoon, Foreign Minister Marise Payne said the personnel being sent to the Ukrainian territories “are not peacekeepers”.
“The Australian government is coordinating closely with the United States, United Kingdom, European Union and other governments around the world to ensure there are severe costs for Russia’s aggression,” she said.
“Along with our partners, we are prepared to announce swift and severe sanctions that would target key Russian individuals and entities responsible for undermining Ukraine’s sovereignty and territorial integrity.
She also said Australian officials still in Ukraine have now been directed to leave the country, with the temporary embassy set up in Lviv earlier this month now closed.
The officials have been deployed to eastern Poland and Romania to assist other Australians seeking to depart Ukraine.
With Evan Young, Reuters.
