OK, so things are tense between Britain and Russia these days. But this breathless headline from the BBC is really over the top: "Russia warns of nuclear defence".The meat of the article is only a little less hysterical:Russia's military chief of staff has said Moscow is ready to use force, including pre-emptively and with nuclear weapons, to defend itself.Under what conditions would Russia use nuclear weapons?In a speech to a military conference broadcast on state-run cable TV, Gen Baluyevsky said there were potential threats to Russia from international terrorism or countries seeking...