Financial Times – 5 June 2012

Although it was necessary during the cold war, Norman Dombey states (Letters, May 29), the British nuclear deterrent is no longer needed as 'the world has moved on, these last 50 years'. He also thinks that the US could disable Russia’s nuclear arsenal with a 90 per cent chance of impunity, and implies that UK Trident missiles carry many more warheads than they actually do.

There is actually no prospect of America achieving a 'first-strike' capability of this sort, given Russia’s ballistic missile submarine forces, which are as invulnerable as our own. Nor is it sensible to base long-term strategic capacity too closely on a reading of current military threats, or the lack of them.

The Trident successor system is required to deter nuclear aggression against this country from any quarter during its project period of deployment – until about 2060. No amount of conventional military strength can achieve this. Of course there have been great changes in the past two decades since the end of east-west confrontation, but there will certainly be many more in the next half-century.

Unfortunately for Professor Dombey and other British unilateralists, we have no way of knowing what those changes will be. That is why a prudent defence policy requires balanced conventional forces to be underpinned by the ultimate insurance policy of a strategic minimum nuclear deterrent, based on the one that successive governments have rightly supported.

JULIAN LEWIS
Visiting Senior Research Fellow
Centre for Defence Studies
King’s College London