President Putin faces a clear choice in how he decides to respond to this appalling tragedy. I hope he will use this moment to find a path out of this festering and dangerous crisis by ending Russia's support for the separatists.

If he does not change his approach to Ukraine in this then Europe and the West must fundamentally change our approach to Russia.

Those of us in Europe should not need to be reminded of the consequences of turning a blind eye when big countries bully smaller countries.