Western nations on Sunday accused Russia of massing tens of thousands of well-equipped troops near the Ukrainian border in preparation for a Crimea-style invasion, while Russia denounced what it said was Ukraine's Russophobic, anti-Semitic leadership.
"Satellite images show that there are between 35,000 and 40,000 Russian troops in the vicinity of the border with Ukraine, equipped with combat aircraft, tanks, artillery and logistical support units," Ambassador Mark Lyall Grant said.
"This is in addition to the 25,000 Russia troops based illegally in Crimea," Lyall Grant added in his speech during an emergency meeting of the United Nations Security Council on Ukraine.
French Ambassador Gerard Araud echoed Lyall Grant's remarks.
The meeting of the 15-nation council, the first emergency session on the Ukrainian crisis in weeks, was convened at Russia's request. Council diplomats said Moscow wanted it to be a closed meeting by France and other Western insisted that it be a public session.
The council has held numerous emergency meetings on Ukraine but has been incapable of taking concrete action because of Russia's sharp disagreements with the United States and Europe.
Last month Russia vetoed a Western draft resolution that would have condemned Crimea's referendum on secession from Ukraine, held when it was already occupied by Russian military forces.
As expected, the council took no action on Sunday.
Russian Ambassador Vitaly Churkin dismissed the criticisms of Russia's actions in Ukraine, telling the council, "Many inaccurate accusations were made against Russia."
He blamed the Kiev government for the unrest across southeastern Ukraine and described its threatened military operation in the region as a "criminal use of force." He was referring to Ukraine's ultimatum to pro-Russian separatists to disarm by Monday or face armed force.
"Things might take an irreversible turn for the worst," Churkin said about the ultimatum, without elaborating.
"The authorities (in Ukraine) do not want to listen to those who do not accept the imposed dominance in Kiev of national radicals and chauvinists, Russophobic, anti-Semitic forces," he said. "The grotesque Russophobia and embedded hatred has become the norm in the Verkhovna Rada (parliament) as well."
Choreographed in Russia?
Kiev has repeatedly said the rebellions across Ukraine are inspired and directed by the Kremlin. But action to dislodge the armed militants risks tipping the stand-off into a new, dangerous phase as Moscow has warned it will protect the region's Russian-speakers if they come under attack.
One Ukrainian state security officer was killed and five were wounded on the government side in Sunday's operation in Slaviansk, Interior Minister Arsen Avakov said.
United States Ambassador Samantha Power suggested that Russia was dissembling about its true intentions in eastern Ukraine, where many Russian-speakers live.
"You have heard these last weeks Russia disclaim any intention of occupying or invading," she said. "You have heard it publicly, and we have heard it privately."
"Unfortunately, the fact is that the armed seizure of buildings in six eastern Ukrainian towns yesterday and several more today mirrors the tactics Russian forces used in the early stages of the Crimea invasion," Power said, adding that the instability "was written and choreographed in, and by, Russia".
Ukraine's envoy, Yuriy Sergeyev, echoed the remarks of Power and other Western envoys, noting that the troops massing near Ukraine were "obviously the professional special forces". He also said, "We don't want any clashes."
Lithuanian Ambassador Raimonda Murmokaite spoke of Russia's "unending provocations" and attempts to dismember Ukraine.
"Where there was no unrest, unrest and chaos are being created by pro-Russian militias, again anonymous without insignia, again carrying the same modern models of assault weapons as seen in Crimea," Murmokaite said.
"Again the external anti-Ukrainian and anti-Western propaganda machine is in full swing, inciting suspicion, mistrust and hatred waiting to explode," she added.
No country on the council spoke out strongly in Russia's defense. Moscow's traditional ally and fellow veto power on the Security Council, China, merely called for all parties in Ukraine to "keep calm and exercise restraint."