The world was trying late on Thursday night to come to terms with the implications of a shocking instance of mass murder in the skies. A smouldering carcass and scattered debris was all that remained of Malaysian Airlines Flight 17, en route from Amsterdam to Kuala Lumpur with 280 passengers and 15 crew on board, which was shot down over Eastern Ukraine. The area—the Donetsk region—is a battleground of a vicious war between Ukraine forces and pro-Russian separatists. At the time of going to press, both the Ukrainian and Russian governments were denying pressing the button (the missile systems, say experts, are too advanced to reach the hands of ragtag separatists), with Ukrainian president Petro Poroshenko calling the tragedy ‘an act of terrorism’. But efforts are on to pacify the situation, for there are fears this could trigger—close on the heels of the Crimean crisis—the biggest Russia-West crisis since the end of the Cold War.