A worker turns a valve at an underground gas storage facility near Striy in western Ukraine in this May 21, 2014 file photo. Russia’s Gazprom said on June 16, 2014, Ukraine had failed to pay at least part of its gas debts by a 0600 GMT deadline and would now have to pay up front for deliveries. Picture taken May 21, 2014. REUTERS/Gleb Garanich/Files (UKRAINE – Tags: ENERGY POLITICS BUSINESS)
