A radical protester uses a slingshot to hurl a stone during clashes with Interior Ministry and law enforcement members on the Day of Ukrainian Cossacks, marked by activists and supporters of the All-Ukrainian Union Svoboda (Freedom) Party and far-right activists and nationalists to honour the role of the movement in the history of Ukraine, during a rally near the parliament building in Kiev, October 14, 2014. The radical protesters demanded the release of political prisoners in Ukraine. REUTERS/Gleb Garanich (UKRAINE - Tags: POLITICS CIVIL UNREST ANNIVERSARY) 

A protester uses a slingshot during clashes with police in Kiev February 18, 2014. Anti-government protesters clashed violently with police in central Kiev on Tuesday, a day after Moscow moved to cement its influence over Ukraine with $2 billion in cash to shore up the former Soviet state's heavily indebted economy. A parliamentary deputy said on Facebook that three demonstrators had been killed, and Ukrainian television said five protesters had been hurt in the clashes. Neither report could immediately be confirmed. REUTERS/Konstantin Chernichkin (UKRAINE - Tags: POLITICS CIVIL UNREST)

Pro-European integration protesters shoot using a big slingshot towards riot police in Kiev January 23, 2014. Ukrainian opposition leaders emerged from crisis talks with President Viktor Yanukovich on Wednesday saying he had failed to give concrete answers to their demands, and told their supporters on the streets to prepare for a police offensive. REUTERS/Vasily Fedosenko (UKRAINE - Tags: POLITICS CIVIL UNREST) 

A pro-European integration protester shoots using a big slingshot towards riot police in Kiev January 23, 2014. Ukrainian opposition leaders emerged from crisis talks with President Viktor Yanukovich on Wednesday saying he had failed to give concrete answers to their demands, and told their supporters on the streets to prepare for a police offensive. REUTERS/Vasily Fedosenko (UKRAINE - Tags: POLITICS CIVIL UNREST) 

Pro-European integration protesters shoot using a big slingshot towards riot police in Kiev January 23, 2014. Ukrainian opposition leaders emerged from crisis talks with President Viktor Yanukovich on Wednesday saying he had failed to give concrete answers to their demands, and told their supporters on the streets to prepare for a police offensive. REUTERS/Vasily Fedosenko (UKRAINE - Tags: POLITICS CIVIL UNREST) 

Pro-European integration protesters shoot using a big slingshot towards riot police in Kiev January 23, 2014. Ukrainian opposition leaders emerged from crisis talks with President Viktor Yanukovich on Wednesday saying he had failed to give concrete answers to their demands, and told their supporters on the streets to prepare for a police offensive. REUTERS/David Mdzinarishvili (UKRAINE - Tags: POLITICS CIVIL UNREST) 

Pro-European integration protesters use a big slingshot during clashes with riot police in Kiev January 23, 2014. Ukrainian opposition leaders emerged from crisis talks with President Viktor Yanukovich on Wednesday saying he had failed to give concrete answers to their demands, and told their supporters on the streets to prepare for a police offensive. REUTERS/Valentyn Ogirenko (UKRAINE - Tags: POLITICS CIVIL UNREST) 

A pro-European integration protester uses a slingshot during clashes with police in Kiev January 20, 2014. Protesters clashed with riot police in the Ukrainian capital on Sunday after tough anti-protest legislation, which the political opposition says paves the way for a police state, was rushed through parliament last week. REUTERS/Vasily Fedosenko (UKRAINE - Tags: POLITICS CIVIL UNREST) 

A pro-European integration protester uses a slingshot during clashes with police in Kiev January 20, 2014. Protesters clashed with riot police in the Ukrainian capital on Sunday after tough anti-protest legislation, which the political opposition says paves the way for a police state, was rushed through parliament last week. REUTERS/Vasily Fedosenko (UKRAINE - Tags: POLITICS CIVIL UNREST TPX IMAGES OF THE DAY) 

A pro-European integration protester uses a slingshot during clashes with police in Kiev January 20, 2014. Protesters clashed with riot police in the Ukrainian capital after tough anti-protest legislation, which the political opposition says paves the way for a police state, was rushed through parliament last week. REUTERS/Vasily Fedosenko (UKRAINE - Tags: POLITICS CIVIL UNREST)