If there is a frontline in Ukraine’s rebellion, it begins at the corner of Kyivsky and Partizanskyi avenues on the north-western edge of the city of Donetsk. Here, all traffic comes to a halt at a makeshift checkpoint consisting of old tyres piled in the middle of the road.This unprepossessing landmark signifies the end of the “Donetsk People’s Republic” – the grand name for the territory held by pro-Russian separatists – and the beginning of a small but vital zone in government hands.Within this area lies Sergey Prokofiev International Airport, which government forces recaptured last month during the bloodiest battle of the crisis. This gleaming terminal was opened as recently as 2012 when, ironically, Donetsk was one of the cities chosen to host the E