Harriet Salem in Sloviansk and Donetsk -

“Stop supporting men hiding behind masks and unmarked uniforms,” US Vice President Joe Biden warned Russia on April 22, in a reference to the pro-Moscow militia groups occupying administrative building across Ukraine’s east. Biden is the highest level US official to visit Ukraine since the crisis erupted.

Kyiv and its western allies have accused Russia of orchestrating the unrest that has rocked Ukraine’s east since the new administration took power in Ukraine following the flight of pro-Russian president Viktor Yanukovych in February. It is a claim that Moscow vehemently denies. Last week the US state department handed an 11-page document to the OSCE that supposedly proves Kremlin interference in Ukraine’s east. Amongst the documents are photographs matching faces of masked militia in eastern Ukraine with soldiers from previous Russian special missions.

The US has threatened Russia with a further round of sanctions if they do not use their influence to halt “provocative actions” of separatists in southeast Ukraine and withdraw the 40,000 troops reported to be stationed on the country’s eastern border.

In a game of mutual finger pointing, Russian Foreign Minister Sergey Lavrov has accused the authorities in Kyiv of doing “nothing to address the underlying causes of the crisis” and instead trying to put “the blame on Russia”.

The verbal exchange follows a shootout in Sloviansk, an industrial city Ukraine’s east, during the early hours of Easter Sunday. The incident, which purportedly left up to four dead and two seriously injured, is shrouded in suspicious circumstances and has shattered the cautious optimism surrounding the fragile four-way Geneva Agreement on de-escalation signed by Russia, Ukraine the EU and US on April 17.

Locals manning the barricade claim that on April 15 four cars of Right Sector, a radical Ukrainian nationalist group, arrived at one of the barricades that ring rebel-held Sloviansk and started shooting at pro-Russia militia. But critics have ridiculed the “proof” of Right Sector’s involvement in the attacks -- pristine documents including the business card of their leader Dymtro Yarosh and several crisp $100 bills – as an overkill of planted evidence. The Ukrainian government has blamed the attack on outside provocateurs.

At a press conference held just hours after the shootout, the self-styled “People’s mayor” of Sloviansk, Viacheslav Ponomarev, called on Russian President Vladimir Putin to send peacekeeping troops, food and arms to the region, which Ponomorev claims is “surrounded by hostile forces”. Wearing his trademark baseball cap and Adidas hoody, the mayor denounced Ukraine’s minister of internal affairs, Arsen Avakov, calling him a “faggot” and claimed he “would personally shoot him in the face” if he came to Sloviansk to negotiate. “This is our land, our territory and we don’t want the fascist junta here,” he said.

Lavrov called the shooting on a religious day “beyond understanding” and claimed the incident is evidence that Kyiv is “unable or willing to control extremists”.

Armed pro-Russia rebels are occupying government buildings in Sloviansk, Kramatorsk, Luhansk and Horlivka. But outside these cities it is unclear whether the separatists hold any real sway. Opinion polls conducted by the Kyiv Institute of Sociology found that 76.8% of people in Ukraine’s southeast do not support the occupation of state buildings by armed men. Only 15.4% said they would support the region’s unification with Russia.

Undeterred by a seeming lack of public support, on April 22 the self-appointed pro-Russian government of the “People’s Republic of Donetsk” announced that a referendum is to be held on the future of the region’s status on May 11. In a somewhat confused speech at a press conference held on the eleventh floor of the occupied regional administration building, the head of the "People’s Republic", Dimitry Pushilin, announced that the referendum would ask local citizens: “Do you support the sovereignty of the Donetsk Republic? Yes or No”.  Exactly how the vote and relevant administration will be organised by the separatists remains unclear.

Opinion is divided as to what Vladimir Putin's game plan is. Ukrainian interim Prime Minister Arseniy Yatsenyuk told NBC on April 22 that: "Everyday, he [Putin] goes further and further. God knows where is the final destination."

According to Nato intelligence, Russia has at least 40,000 troops stationed on Ukraine’s eastern border. But local analyst and history professor at Donetsk University, Igor Todorov, says that whilst a Crimea-style annexation “cannot be ruled out”, since such an act would be very costly, most likely the current goal is simply to “destablise the region as much as possible”. Continued unrest in Ukraine’s east could result in the Ukrainian presidential election, scheduled for May 25, being cancelled or declared illegitimate.