Convoys of armoured vehicles have been seen rolling across the separatist-controlled territories. It wasn’t immediately clear if they were Russian.
Russian officials haven’t yet acknowledged any troop deployments to the rebel east, but Vladislav Brig, a member of the separatist local council in Donetsk, told reporters the Russian troops already had moved in, taking up positions in the region’s north and west.
Linda Thomas-Greenfield, the US Ambassador to the UN, said an “attack on Ukraine was an attack on the sovereignty of every UN member state and the UN charter”.
“Today, President Putin made a series of outrageous false claims about Ukraine, aimed at creating a pretext for war,” Ms Thomas-Greenfield said.
“He claimed that Ukraine is seeking nuclear weapons from the West. This is not true.”
She said it was “nonsense” that Russian troops in the separatist eastern regions of Ukraine were peacekeepers.
“If Russia invades Ukraine even further, we will see a devastating loss of life and unimaginable suffering,” Ms Thomas-Greenfield said.
“In essence, Putin wants the world to travel back in time to … when empires ruled the world. But the rest of the world has moved forward.
“It is not 1919, it is 2022.”
Other members of the UN security council followed the tone of message coming out of Washington, that Russia should back down immediately and avert bloodshed and instability in Europe.
However, it is virtually certain the Security Council will not take any action or issue any statement because Russia has veto power.
Russian diplomat Vasily Nebenzya, who is the current president of the UN Security Council, denied Russia was an aggressor and said a diplomatic solution was still possible.
He also hit out at the US for its “extremely negative role” in “egging on Ukraine” to drift to the West.
The West had also been “unashamedly cramming weapons” into the Ukraine over the past weeks, he claimed, as well as sending in military advisors and instructors to mobilise support.
A long-feared Russian invasion of Ukraine appeared to be imminent today, if not already underway, with Mr Putin ordering forces into separatist regions of eastern Ukraine.
A vaguely worded decree signed by Mr Putin did not say if troops were on the move and it cast the order as an effort to “maintain peace.”
But it appeared to dash the slim remaining hopes of averting a major conflict in Europe that could cause massive casualties, energy shortages on the continent and economic chaos around the globe.
Mr Putin justified his decision in a far-reaching, pre-recorded speech blaming NATO for the current crisis and calling the US-led alliance an existential threat to Russia.
Sweeping through more than a century of history, he painted today’s Ukraine as a modern construct that is inextricably linked to Russia.
He charged that Ukraine had inherited Russia’s historic lands and after the Soviet collapse was used by the West to contain Russia.
Speaking at the UN meeting, Ukrainian diplomat Volodymyr Yelchenko likened Russia to a “virus” and said the members of the security council were “sick”.
“That’s a matter of fact,” he said.
“It’s been hit by the virus spread by the Kremlin.”
He condemned Russia’s sending of troops to Ukraine’s east, and urged the UN to do everything it can to stop a Russian invasion.
Mr Putin’s directive to send in troops came hours after he recognised the separatist areas of Donetsk and Luhansk in a rambling, fact-bending discourse on European history.
The move paved the way to provide them military support, antagonising Western leaders who regard such a move as a breach of world order, and set off a frenzied scramble by the US and others to respond.
US Secretary of State Antony Blinken said Mr Putin’s decision to recognise Donetsk and Luhansk as independent “represents a complete rejection of Russia’s commitments under the Minsk agreements”.
The White House issued an executive order to prohibit US investment and trade in the separatist regions, and additional measures — likely sanctions — are expected to be announced in the coming hours.
Other Western allies also said they were planning to announce sanctions.
British Prime Minister Boris Johnson said Tuesday the UK will also introduce “immediate” economic sanctions against Russia, and warned Putin is bent on “a full-scale invasion of Ukraine … that would be absolutely catastrophic.”
Johnson said Putin had “completely torn up international law” and British sanctions would target not just the regions of Donetsk and Luhansk but “Russian economic interests as hard as we can.”
EU foreign policy chief, Josep Borrell, said that “Russian troops have entered in Donbas,” adding that “I wouldn’t say that (it is) a fully fledged invasion, but Russian troops are on Ukrainian soil” and the EU would decide on sanctions later on Tuesday.
Chinese Foreign Ministry spokesperson Wang Wenbin on Tuesday said China would “continue to stay in engagement with all parties,” continuing to steer clear from committing to back Russia despite the close ties between Moscow and Beijing.
A summit between Mr Biden and Mr Putin is unlikely, a senior administration official said, following intelligence and indications on the ground that Russia is likely to take military action.
On Sunday, White House Press Secretary Jen Psaki said Biden agreed “in principle” to a meeting with Mr Putin as long as Russia does not further invade Ukraine.
But the official said intelligence reports indicated further Russian military action would preclude any leader-to-leader summit.