How did a ragtag guerrilla army get hold of such a sophisticated weapon such as a Buk surface-to-air missile, and what else does it have in its arsenal?
Pro-Russian separatists in eastern Ukraine have been portrayed as a motley band of militiamen with ageing guns and mismatched uniforms.
But western politicians and intelligence services now believe the separatists used a Russian-made Buk surface-to-air missile to knock Flight MH17 out of the sky at 32,000 feet.
So how did a ragtag guerrilla army get hold of such a sophisticated weapon, and what else does it have in its arsenal?
Military experts say the rebels began to build up their stocks in April when numerous armoured personnel carriers – or “battlefield taxis” – came into their possession. They seized some from overrun Ukrainian bases, while others were used to transport volunteer fighters from Russia into the conflict zone.
Yet more deadly in the separatist armoury is the Grad (Hail) artillery unit. Grad launchers may not have been supplied by Russia, but spare missiles could have been smuggled and some have “gone missing” from Ukrainian units.
The Grad is a highly effective truck-mounted multiple rocket launcher which can be used to saturate an area of ground quickly with intensive fire. At least 19 servicemen were killed on July 11 when the rebels hit a Ukrainian column with a salvo of Grad rockets.
Yet according to Mark Galeotti, an expert on Russian military and security affairs, the real “game-changer” in the rebels’ hands is the now infamous Buk missile system…