In early February, when Vladimir Putin’s troops were on the Ukrainian border and much of the world thought he was bluffing, the Russian military’s guidance on mass graves was changed. Bodies should be covered with chemicals, diagrams showed, and then rolled over by a bulldozer to flatten the ground. The advice seemed so grotesque as to be a decoy: surely a brutal invasion would not be so clearly signalled?

The story of the mass grave found in Bucha shocked the world because it represents how fast things have deteriorated and that we are now seeing the kind of barbarism Europe thought...