The second lesson is to remember the modesty of our deterrent. At any given time, 16 Trident missiles are available on board one Vanguard class submarine – less than half the number of delivery systems that Mr Putin will deploy this year. Incidentally, the planned “Successor” submarine will carry only 12 missiles. So our nuclear deterrent is minimal and defence spending too low. The former must be renewed – and the latter increased as quickly as possible.