Was it ever revealed/implied who were the other Involveds behind the plot? * No, it wasn't. The Masaq' Orbital Mind even suggested it might be a faction of the Culture, trying to prevent the Culture as a whole becoming complacent and decadent. * Though the latter seems unlikely as insiders should have been aware of the limitations of the Culture's mind-scanning taboo. * Which could have been the point. A faction of the Culture might not want another genocide but still want to make a threatening point about what The Culture had done. * Seems far too costly. The message would have still been heard with a hundred times less civilian casualties.