Black smoke billows from Donetsk international airport  duringa  heavy gun battle between the Ukrainian army and pro-Russian militants in the eastern Ukrainian city of Donetsk on May 26, 2014. Ukraine scrambled fighter jets and combat helicopters to strike rebel gunmen who seized control of the main airport in the eastern city of Donetsk on May 26, triggering heavy gunbattles and Ukrainian combat helicopters hitting an airport terminal. The fierce confrontation erupted after Ukrainian oligarch Petro Poroshenko, who claimed victory in Sunday's crucial presidential election, vowed to press on with an offensive against pro-Russian separatists waging a bloody insurgency across the east. AFP PHOTO /  OLEXANDR STASHEVSKIY        (Photo credit should read OLEXANDR STASHEVSKIY/AFP via Getty Images)