What Brought Down Flight MH17 Over Eastern Ukraine?

An Emergencies Ministry member walks at a site of a Malaysia Airlines Boeing 777 plane crash near the settlement of Grabovo in the Donetsk region, July 17, 2014. Maxim Zmeyev/Reuters

What caused Malaysia Airlines flight MH17 to crash into a field in eastern Ukraine killing all 295 on board? The truth will only be known when someone admits to causing the plane to crash, when satellite data reveals whether it was shot down or crashed, or when the full investigation, some months off, gives its final report.

[Related: Malaysia Airlines Plane May Have Been Shot Down, Ukrainian Officials Say; 295 Killed]

However, trying to make sense of the disaster, reporters are putting to experts on aviation and ground-to-air weapons a number of alternative scenarios. Here are the options that are being explored:

1. Kiev forces shot down the plane on purpose. Highly unlikely and the Ukrainian president, Petro Poroshenko has firmly placed the blame on the separatist rebels who hold the part of eastern Ukraine where the plane was downed.

The war is slowly turning in favor of the Kiev government forces, so it would be rash to invite international condemnation for such a blatant act of unnecessary aggression against a civilian airliner of a third-party country.

2. Kiev forces shot down the plane by accident. Possible but still unlikely as the Kiev forces are well trained and disciplined and are under clear instructions to do nothing that might provoke the wrath of the U.S. and E.U.

3. Pro-Russian separatists shot down the plane on purpose. Possible as they have shot down a number of Kiev forces military aircraft before, though those planes and helicopters were flying far lower than flight MH17.

However, the separatist rebels may have been trying out a weapon, though they deny their Russian provided weapons are capable of reaching airline routes. But as the rebels are the least disciplined of the forces under scrutiny, this may ultimately prove to be the true explanation.

Confident that the crash was "a terrorist act" by Ukrainian separatists, Poroshenko has invited Dutch investigators to determine exactly what happened. Separatist forces on the scene have taken control of the black box recorder that will hold the key to what happened.

Shortly after the plane hit the ground, Igor Girkin, a separatist took to the VKontakte social network with: "We just downed an An-26 near Torez. It's down somewhere near Progress mine." That may have been merely an empty boast. Not long after, the post was removed.

4. Pro-Russian separatists shot down the plane by accident. Possible. Though as they hotly deny responsibility for the crash and insist they do not have the weapons to pull off such a trick, only a full investigation will reveal who fired the missile, if indeed MH17 was shot down.

5) Russian military missiles shot down the plane on purpose. Highly unlikely. Having suffered renewed and painful U.S. and E.U. sanctions this week, Russian President Vladimir Putin does not want to escalate tensions in the Ukraine further. On the contrary, everything he has been doing and saying lately has suggested he wishes to play down Russian involvement in the Ukraine conflict. Putin will know from his military's satellite pictures whether the plane was shot down or crashed.

6. Russian military missiles shot down the plane by accident. Again, highly unlikely. No one in the Russian military dare make a move unless it has been given the OK from the Kremlin. Putin has ruled out direct military involvement not least because he has been getting his own way in Ukraine by stealth.

7. It was an accident caused by mechanical or pilot failure. Always possible, but unlikely. The Boeing 777 like the one that crashed is one of the safest airliners flying today.

8. MH17 was brought down by an act of terrorism, either by a terrorist on board or by the planting of a bomb. Unlikely. Usually acts of terrorism are claimed by the terrorist organization responsible without delay, and no one has yet claimed responsibility.