The defence secretary announced on Monday a few million pounds' spending on developing a capability to replace Trident, Britain's independent nuclear deterrent. Listening to some discussions of this on the radio, I heard some things that were useful; but I also thought some things were left out of the discussion. I thought I might try to fill in a few of the gaps.
First of all, a health warning: I take money from the defence secretary and his minions to teach Army officers. I don't, however, take money from the defence secretary to say nice things about the way we defend the United Kingdom; so my academic freedom gives me a large measure of objectivity.
Trident and Tomahawk
We currently deter our enemies from attacking us by hiding Trident missiles in our Vanguard-class submarines under the sea.
Trident missiles fire almost straight up into space, pushing a rack of small but powerful hydrogen bombs ahead of them. Then the bombs re-enter the Earth's atmosphere and drop very accurately onto different places. They are so small and move so quickly that stopping them is almost impossible.
Trident missiles have a range of more than 4,500 land miles. This means that the submarines that carry them can hide in the ocean without having to be particularly close to their targets. In turn, this means that if you want to attack the UK you have no reliable way of getting rid of the Trident missiles first.
Some have recently suggested substituting a much cheaper sea-launched cruise missile such as Tomahawk for the more expensive Trident in its more expensive subs.
Tomahawk can be fired from the Royal Navy's new Astute-class submarines; and although we generally use high explosives in these missiles, Tomahawk was originally designed to carry a small but powerful hydrogen bomb to its target.
Cruise missiles are, essentially, unmanned aircraft which get to a target and then blow up. They are not especially fast, but their small size makes them hard to spot with radar. They carry enough fuel to fly about 700 land miles.
As a thought experiment, imagine somebody in Central Asia who wanted to attack the UK. Put that person somewhere in Uzbekistan or Kyrgyzstan, and he could feel completely safe from Tomahawk missiles since those countries are more than 1,000 miles from the nearest bit of sea.
A submarine carrying Trident could be off Phuket or Sevastopol or anywhere nearer than Madagascar and still strike a target in central Asia. The harder the missile base is to find, the better its deterrent value and the greater the resulting stability, so a Vanguard boat carrying Trident gives immense stability. A submarine carrying Tomahawk missiles would have to move close to the aggressor that was threatening the UK, which makes it easier to find and which increases the opportunity for the aggressor to find and destroy the submarine and its missiles. An Astute boat with Tomahawks is much cheaper than a Vanguard boat with Tridents, but it buys a lot less stability.
Deterring chemical, biological, radiological and nuclear weapons
Remember weapons of mass destruction? That's a category created for one purpose: permitting Western countries to deter chemical or biological attack without developing and maintaining arsenals of chemical or biological munitions.
Threatening to retaliate against chemical or biological attack using conventional explosives isn't especially impressive. We use conventional explosives against people who don't attack us at all, as Colonel Ghaddafi could tell you if he were alive today.
If we didn't have an effective nuclear deterrent, we would only very weakly be able to deter an attack on the UK using biological or chemical warfare. Since biological and weapons are potentially easy and inexpensive to make, this a significant weakness. Since we often deploy our armed forces on expeditionary operations, potentially exposing them to biological or chemical attack, the price of a good nuclear deterrent can be viewed as buying a lot of freedom of action for our forces overseas.
Indiscriminate attack
The first and only time nuclear weapons have been used in war was against cities. This was in the Second World War when we the Allies were already destroying cities with conventional bombs, including firebombs. During the Cold War the narrative of destroying cities was a powerful one, but not the only one embraced by nuclear strategists and planners.
Targeting cities is called 'countervalue' targeting because weapons are turned against things enemy governments value like cities. Governments value cities in wartime because they are filled with railway yards, ports, factories and people. Countervalue targeting has a special place in deterrence theory because a city isn't going anywhere.
Targeting enemy weapons, trying to destroy them before they can be used, is called 'counterforce' targeting. Counterforce is a lot less morally queasy because you're targeting other nuclear weapons, military equipment and military people. However, counterforce targeting tempts you (and your enemies) to shoot first, to disarm an opponent before you are disarmed by an enemy strike. Countervalue targeting makes for more stability because whether you shoot now or shoot later the city is still a big fat target.
During the Cold War, NATO was prepared to use battlefield nuclear weapons to counter the vast numbers of Soviet and Warsaw Pact tanks. This version of counterforce targeting was meant to make the Soviets think twice about trying to use their massive numerical advantage against the West. This kind of counterforce deterrence helped create stability, or at least a useful perception of stability, in Europe.
Tomahawk and Trident are very accurate. The warhead in Tomahawk can be adjusted to yield a very small explosion (very small for a hydrogen bomb, that is). Trident missiles fly with the bomb yields set in advance, but a future programme could be designed around very low-yield devices. The combination of low yields and high accuracy could produce a system no more indiscriminate than unguided conventional bombs.
So, in summary:
- A future deterrent that is more like Trident than like Tomahawk would cost more but probably provide a lot more stability.
- Nuclear weapons may be filthy, but they are a comparatively clean way of deterring people from using biological and chemical weapons which are worse.
- Just because nuclear weapons can be indiscriminate city-smashers doesn't mean that's the only way nuclear weapons can be used.