Russia and the US traded barbs Wednesday ahead of high-level talks on the crisis in Ukraine as a military operation ordered by Kiev to oust pro-Moscow separatists in its eastern regions collapsed.
Pro-Russian activists block a collumn of Ukrainian men riding on Armoured Personnel Carriers in the eastern Ukrainian city of Kramatorsk on April 16, 2014
A concerned NATO said it was deploying more forces in eastern Europe and called for Russia to stop "destabilising" the former Soviet republic, which has been in deep turmoil since the ouster of pro-Kremlin president Viktor Yanukovych in February.
The Ukrainian government's decision to put down a separatist uprising in its industrial heartland appeared to backfire spectacularly after an earlier warning from Moscow that Kiev was dragging the country to the brink of civil war.
Ukraine's defence ministry said Moscow-backed militants blocked and seized six armoured vehicles that had been dispatched to root out the separatists.
The commandeered vehicles, some adorned with Russian flags, were then stationed in the centre of the town of Slavyansk surrounded by dozens of armed men in camouflage claiming to be volunteers and Ukrainian army defectors, an AFP reporter said.
In another apparent embarrassment on the outskirts of the nearby town of Kramatorsk, Ukrainian troops -- some weeping -- handed over the firing mechanisms of their rifles to pro-Moscow protesters who had surrounded their column of 14 armoured carriers in return for a promise they could leave in their vehicles, an AFP reporter said.
As the government's push to reclaim authority unravelled, NATO chief Anders Fogh Rasmussen announced the alliance would deploy additional forces in eastern Europe.
"We will have more planes in the air, more ships on the water... and more readiness on the land," he said, while adding that a political solution was the only way forward.
The Ukrainian government ratcheted up the verbal attacks on Russia, with Prime Minister Arseniy Yatsenyuk accusing Moscow of trying to build "a new Berlin Wall".
Yatsenyuk demanded Moscow halt its support for the separatists and said Kiev would take a tough line at Thursday's crunch talks between the top diplomats of Russia, the European Union, the United States and Ukraine in Geneva.
"There is only one directive for the Ukrainian foreign ministry: the Russian government has to immediately withdraw its commando groups, condemn the terrorists and demand they leave the installations," he said.
Russia lashed out at the White House ahead of the summit, claiming the Obama administration was backing Kiev's "war on its own people" in strident language that makes any concession at the talks seem unlikely.
"In Washington they have to be aware of the catastrophic consequences of their reckless support for their underlings in Kiev," the Russian foreign ministry said in a statement.
But the United States demanded that Russia stop its "provocation" in eastern Ukraine and threatened that it was actively preparing new sanctions against the Kremlin.
- 'Shoot-to-kill' policy -
As Kiev's operation against the separatists floundered, Ukraine's acting Defence Minister Mykhailo Koval headed out to the east in a bid to salvage the situation.
The military in Kiev also pledged a firm response after two serviceman were allegedly taken hostage by pro-Russian forces in the Lugansk region.
The Ukrainian Security Service (SBU) claimed in a statement that Russian commanders in the east had issued pro-Kremlin militants with "shoot-to-kill" orders.
Vitaliy Naida, a spokesman for the service's counter-intelligence department, said some 40 Russian spies had been uncovered and stopped since the operation in the east began.
Elsewhere, pro-Moscow gunmen stormed the mayor's office in the regional capital Donetsk, according to an AFP reporter.
- 'Sharp escalation' -
On Tuesday, confident authorities in Kiev had launched what they called the "anti-terrorist operation" to much fanfare, sending tanks towards Slavyansk -- which has been under the control of pro-Russian gunmen for several days -- in a high-risk strategy sharply condemned by the Kremlin but supported in Washington.
The display of military hardware was the most forceful response yet by the Western-backed government to the pro-Kremlin militants' occupation of state buildings in nearly 10 cities across Ukraine's rust belt.
But the move drew a sharp response from Putin in a telephone conversation with German Chancellor Angela Merkel.
"The Russian president remarked that the sharp escalation of the conflict has placed the country, in effect, on the verge of civil war," the Kremlin said in a statement.
The White House on Tuesday described Ukraine's decision to deploy troops as a "measured" response to a lawless insurgency that had put the government in an "untenable" situation.
- Threat of counterstrike -
Kiev's untested interim leaders -- who took power in February after four months of pro-European protests ousted Yanukovych -- have struggled to deal with the high-stakes insurgency in the east.
The breakaway move could potentially see the vast nation of 46 million people break up along its historic Russian-Ukrainian cultural divide.
Moscow last month annexed the largely Russified region of Crimea after deploying military forces there and backing a hasty local referendum calling for the Black Sea peninsula to be absorbed into the Russian Federation.
Ukrainian intelligence said Wednesday it had intercepted communications showing that the same Russian agents who oversaw the seizure of Crimea were now coordinating the unrest in the east.
Moscow has repeatedly claimed it has no ties to the Russian-speaking gunmen who have proclaimed the creation of an independent republic in the east.
But a forceful military response by Kiev could prompt a devastating counterstrike by Russian troops who are waiting to act on Putin's vow to "protect" Russian-speakers in the neighbouring state.