Referring to Sir Michael Quinlan, Brian Wicker asserts categorically (Letters, 16 May) “our nuclear weapons have always been targeted on cities”. In a private conversation when he was still the head civil servant at the Ministry of Defence, Sir Michael told me that they were in fact targeted according to military criteria, with civilian loss of life kept to a minimum (which of course could still mean a large number). I deduced he was talking mainly about Warsaw Pact tank concentrati