Into the maelstrom

This is what we know so far:

• At 4.41 pm BST today Reuters.uk reported that a Malaysian airplane had crashed on the ground in eastern Ukraine.
• The flight was MH17 from Malaysian Airlines flying at 10 kilometre altitude from Amsterdam to Kuala Lumpur.
• An official from the Ukrainian Ministry of the Interior stated the plane had been shot down by a BUK surface-to-air missile, and that all 295 passengers and crew had died. The Ukrainian government stated it was not involved, and suggested the plane may have been shot down, comparing it to recent attacks by separatists on Ukrainian military planes.
• Aleksandr Borodai, prominent in the separatist forces, claimed the plane had been shot down by the Ukrainian Air Force.
• A range of commercial airlines have declared they now will not fly over eastern Ukraine.

It is now certain that the plane did crash, leading to the death of almost 300 people. Which are the possible explanations for this horrific event?

1. Could the airplane have crashed by itself? This is highly unlikely. There are no reasons to suspect that the plane should have malfunctioned to the point of crashing; air traffic controllers claim all messages from the plane were normal until it disappeared from their screens.
2. Could the airplane have been hit by a bomb; either in the hold or a suicide bomber? There is little reason to suspect that a bomb should have been slipped through the safety checks at Schiphol Airport; and it would be a remarkable coincidence if a bomb in the airplane would detonate precisely over an active combat zone where military planes were shot down just days ago.
3. Could the airplane have been shot down by the Ukrainian military? These troops would have the ability to shoot down the airplane, but it is difficult to see why they should do so. There is little reason why the Ukrainian military should have mistaken the airplane for a separatist plane, consider the separatists have not flown any airplanes so far. 
4. Could the airplane have been shot down by the separatists in Ukraine? It is possible that the separatists have acquired the BUK missile systems that allegedly was used to shoot down the plane, but it is difficult to see why they should have done so, or why they should have mistaken the airplane for a military airplane, especially given the height at which it was flying. An analyst on BBC has speculated, however, that the separatists, unlike governments, might not be able to distinguish electronically civilian versus military aircraft.

If, and this remains a big if, the airplane was shot down deliberately there remains the question of motive. 

• Why would the Ukrainian military shoot down the airplane? Ukraine is winning the military battle in the region and has little reason to escalate the conflict.
• Why would the separatists shoot down the airplane? They are losing the battle but shooting down a civilian airplane would not help their cause.
• Why would any Russian-led forces shoot down the airplane? Elements in the Russian state may have an interest in keeping the trouble in eastern Ukraine going to some extent, but scaring international airlines from using the airspace makes little political, military or commercial sense.

There remains one, very remote, possibility that some party wants to use this catastrophe to escalate the current crisis beyond the area to which it has so far been contained. If this is the case - and I have currently seen no strong indications that it is the case - then the reasonably calm reactions from all sides so far is a sign that such a plan might fail.

This does not mean that a possible shooting down of the aircraft should not have consequences for the parties responsible; even if this was a mistake. But the next days must be focused on fact-finding before such steps are taken.