Rethinking Deterrence

'What deterrence needs is ambiguity. We don't know much about North Korea's nuclear capability, but we're certainly not going to risk nuclear annihilation by taking them on, even if the risk were 50 per cent, 25 per cent or just 10 per cent. That's why Israel is so sensitive about its nuclear secrets being revealed. The less other countries know about your nuclear capability, the more effective will be its deterrence.

The trouble with Britain's is that, when it's not at sea, it's highly visible. Every time a Trident submarine comes back to dock, the local residents around Faslane know about it. So if all the Trident subs were there at once, it would theoretically be possible for an adversary to launch a surprise attack and destroy them all. That was the worry during the Cold War, which led to the Continuous At Sea Deterrence (CASD) policy that we've adopted ever since.

Even in those days, the chances of the Soviet Union launching a first strike against Britain were vanishingly small. Now they're imperceptible. Our main enemy now is not even a state â?? it's organisations such as al-Qa'ida, whose foot soldiers are British citizens with rucksacks. If they use weapons of mass destruction on our soil, we're hardly going to launch a nuclear attack in response. Where would we send it?

Our nuclear deterrent is only of use against state enemies. And if tensions were to rise against â?? say â?? Russia or China, we would have plenty of warning. This is the premise of a paper written by Professor Malcolm Chalmers for the Royal United Services Institute, published last week. He argues that we don't prepare our conventional forces for a surprise attack by another state against the UK, so we shouldn't do the same for our nuclear forces. It's our insistence on CASD for Trident's replacement that is making it so expensive. Instead, he says, we could reduce the number of submarines from four to three or two.

'