Prospects of a diplomatic solution to the crisis in eastern Ukraine became grimmer on Tuesday as Ukrainian forces launched an operation to retake facilities seized by pro-Russian militants, while Russian and Western leaders dug in on their divergent interpretations of who is to blame for the escalating confrontation.
Ukrainian authorities said that government forces launched a "special operation" against militiamen in the country's Russian-speaking east, recapturing a military airfield from pro-Moscow separatists.
Gunfire could be heard from the airfield at the town of Kramatorsk after a fighter jet swooped low over the area. Ukrainian troops were seen disembarking from helicopters.
In Kramatorsk, four military helicopters could be seen over the airport. Two of these landed and when troops stepped out and walked across the field, locals manning a barricade shouted "Shame! Go back home!"
Acting Ukrainian President Oleksander Turchynov had earlier announced that a military operation was under way to flush pro-Russian separatists out of the government buildings and facilities they have seized in about 10 towns and cities in the east over the last few days.
Turchynov issued a statement saying Ukraine had retaken the airfield in Kramatorsk from pro-Russian militants, while the state security service said an "anti-terrorist" operation was in progress against separatists in the nearby town of Slovyansk.
Turchynov said the government's military operation was intended to "protect Ukrainian citizens, stop the terror, violence and attempts to tear our country to pieces" and that force would be used "responsibly."
As the military operations began, Russia and the West continued their war of words over who is to blame for the crisis. President Vladimir Putin's spokesman strongly denied on Tuesday that there were any Russian troops in Ukraine, despite Western governments' accusations that Moscow supported the armed men who seized government buildings in eastern Ukrainian towns.
"This is an absurd assertion," Dmitry Peskov said during a conference call. "There are no Russian troops there."
Peskov's comments followed Putin's recriminations in a telephone conservation with U.S. President Barack Obama on Monday night during which he said claims that Russia was interfering in Ukraine were based on "inaccurate information."
United Nations Report
The two sides engaged in more verbal sparring over a United Nations report released Tuesday that said ethnic Russians in eastern Ukraine have falsely claimed to be under assault to justify Russian intervention.
"Although there were some attacks against the ethnic Russian community, these were neither systematic nor widespread," the UN human rights office said in its report issued after two visits to the former Soviet republic last month by UN Assistant Secretary-General for Human Rights Ivan Simonovic.
"Photographs of the Maidan protests greatly exaggerated stories of harassment of ethnic Russians by Ukrainian nationalist extremists," it said, "and misinformed reports of them coming armed to persecute ethnic Russians in Crimea were systematically used to create a climate of fear and insecurity that reflected on support to integration of Crimea into the Russian Federation."
Gianni Magazzeni, head of the rights office's Americas, Europe and Central Asia branch, told a news conference that the report aimed to encourage an environment for free and fair elections in Ukraine on May 25.
But Russia sharply criticized the report, saying it was "one-sided, politicized and not objective."
"One gets the impression that the report was fabricated to correspond with conclusions formed in advance," the Russian Foreign Ministry said of the document.
Since the beginning of unrest in eastern Ukraine, the West has accused Russia of supporting armed militants, an accusation Moscow has rebutted repeatedly, arguing that Ukraine is on the brink of a "civil war" of Kiev's making. Russian officials, who deem the current Ukrainian government illegitimate, have berated it for "its unwillingness and inability" to consider the interests of the Russian and Russian-speaking population of eastern Ukraine.
Tarik Cyril Amar, an assistant professor at Columbia University who specializes in Russian, Ukrainian and Soviet history, said the reality was less clear-cut than either side was making it out to be.
"There is evidence that there are Russian agitators in eastern Ukraine," Amar said in a telephone interview. "But to overemphasize this point is not doing a favor to Ukraine. Such disruption has been made possible by underlying tensions in the eastern part of the country. Our analysis needs to go beyond solely blaming Russia."
Amar also said that eastern Ukraine's "de facto" slippage from central control was tied more to domestic issues in the region, including local authorities' split loyalties and their distrust of Kiev.
In Luxembourg, NATO Secretary General Anders Fogh Rasmussen urged Russia to "stop destabilizing the situation in Ukraine, and make clear that it does not support the violent actions of pro-Russian separatists" at a meeting of EU defense ministers on Tuesday.
Rasmussen came to brief EU defense ministers on what NATO is doing to counteract what Western countries have denounced as a Russian campaign of pressure and intimidation against Ukraine.
He said NATO plans a three-fold response: "reinforced defense plans, enhanced exercises and appropriate deployment" to reassure NATO member states nearest Russia that the alliance has their back.
Asked by reporters if NATO could create military bases in its Eastern European members, Rasmussen said it was too early to go into details.
"But no one should doubt our determination to ensure effective defense protection of all allies," he said.
Material from Reuters is included in this report.