Suppose a rebel army mounts a raid on government forces that ends with the cold blooded execution of prisoners. Country ‘A’ donated the satellite phones that were used to organise the operation, while the weapons came from country ‘B’. Inadvertently, these two nations jointly gave the insurgents the means to commit a war crime. But are they equally responsible? Or is the government that handed over the satellite phones less culpable than the one that supplied the lethal weapons?