This week's condemnation of the head of our Armed Forces is the most public of the stoushes the leader of the Labour Party has got into. It is also probably the most reckless. At the best of times Labour are't trusted as much as the Tories on defence, and these are far from the best of times. It is possible to argue that the row doesn't damage Labour but that is only because the public already know what they think about Corbyn's Labour and defence. Voters don't trust him at all on the issue. The very fact that he would undermine the doctrine of deterrence by publicly declaring that he would not use nuclear weapons is the very reason that he will never get the chance to put that view into practice – no-one with such views will be allowed by the electorate to become Prime Minister.