|Evidence of gunfire at the cockpit|
All the blah-blah about Buk missiles and who owns them was just a smokescreen. The availble evidence from the ground shows that the airplane was shot down with machine gun fire, which could only originate in the two Ukrainian fighter jets that were "escorting" the civilian flight.
Veteran pilot Peter Haisenko wrote an article for Global Research on the matter. He says about the only available high resolution image of the remains (→ PDF format):
The facts speak clear and loud and are beyond the realm of speculation: The cockpit shows traces of shelling! You can see the entry and exit holes. The edge of a portion of the holes is bent inwards. These are the smaller holes, round and clean, showing the entry points most likely that of a 30 millimeter caliber projectile.
The SU-25 machine guns use 30mm ammo of two types, one splinter explosive (dum-dum) and the other anti-tank incendiary, intercalated so they maximize the possible damage.
Because the interior of a commercial aircraft is a hermetically sealed pressurized chamber, the explosions will, in split second, increase the pressure inside the cabin to extreme levels or breaking point. An aircraft is not equipped for this, it will burst like a balloon. This explains a coherent scenario.
While the OSCE is not being as specific, the descriptions so far do match the reconstruction by Haisenko:
Michael Bociurkiw of the OSCE group of monitors at his daily briefing described part of the plane’s fuselage dotted with “shrapnel-like, almost machine gun-like holes.”
Some have tried a last-ditch defense of the Buk missile hypothesis arguing that the holes could have been also caused by shrapnel from such a missile (not a direct hit in any case) but this is contradictory with the evidence as well because there are not just entry holes but also exit ones and the entry holes are very round, as correspond to bullets, not chaotically produced shrapnel.
Please follow the in-like links for further information.