Question:

You spoke about the need to keep ourselves protected and that is why it is appropriate to maintain the nuclear deterrent. But ours is not an independent deterrent - we are dependent on US permission to use it. Why do I say that? Of course the first salvo is under our control - but the replacements are not and if firing took place without US permission they would simply refuse to re-stock. So it is not an independent system at all.

Defence expenditure used to be an excellent way to manage our economy - when the state needed to throw extra money into the mix, it ramped up defence expenditure - and cut it back again when private enterprise was absorbing an appropriate amount of capacity. Then the EEC became the EU and the rules on procurement were changed..... Now when we wish to replenish capital ships, we have to tender within the EU and France gets the business. What craziness is this!

So we spend our scarce £s on US-supplied missiles and EU-supplied capital ships. Is it any wonder that our economy is in tatters!

Let us stop the nonsense and protect the national interest first. If we want an independent deterrent let us create our own. Let us generate local employment with our own defence industry.

Answer:

A nuclear war is probably a one-shot war anyway, so I'm not too worried about "reloading" quickly. It's there as a deterrent. If the deterrent fails, we're in a different world anyway.

Defence expenditure was never a net economic contributor. It was dressed up like that by politicians who thought they needed to describe it that way to sell it, but fundamentally it is an example of the broken-window fallacy (closely-related to the Keynesian delusion - see http://en.wikipedia.org/wiki/Parable_of_the_broken_window). When you think about it, defence is inherently destructive, not creative. Good defence creates conditions within which people have sufficient security to create wealth (and from that, pay for the defence that allows them to continue to do so), but it is pure consumption in its own right. Defence of the realm is a necessary cost for a nation, not a tool for economic management.

The idea that we maximise the wealth of the nation by trying to retain as much as possible of our money within our borders (by buying only from ourselves) is called mercantilism, and was demolished by Adam Smith (and many others). Protectionism and "industrial policy" are dilute forms of the fallacy. We need not to impose on our businesses and workforce unnecessary burdens (or constraint of choice and competition, as in the EU rules you cite), but it is highly unlikely that we will be the best at producing every type of military product there is. If we are not, then by obliging our military to "buy British", we would be deliberately condemning them to inferior equipment.

And if we will not buy from others, they will not buy from us, and we can expect our arms industry (which is still relatively successful, whether or not one is comfortable with it) to lose its export market. We have to buy goods from foreigners so that they have money to buy goods from us. And we should want to anyway, because it is quite likely that other nations will have comparative advantages over us in the production of some of these goods, just as we should have comparative advantages over them in others. We are all made poorer if we choose to produce the things we are ill-equipped to produce as well as the things we are well-equipped to produce, rather than each doing what we are good at and trading with others for the products that they are good at producing. The above holds true even where it seems that one country has a comparative advantage over another in all regards (see David Ricardo and the law of comparative advantage).

Defence decisions cannot be treated as simply another category of public spending. Though there are clearly limits, defence against a material threat (even one that is not immediate or well-formed) must take priority over other government expenditure. The question in defence is what are the threats, how best are they deterred, what can we afford to do, and what can we not afford not to do.

There is always a danger of fighting the last war when planning defence spending. That is happening now, with generals and politicians arguing that we should be spending most on ground troops because that's what we've been using in Afghanistan and Iraq. I also believe that we should have enough troops well-enough equipped to provide a credible ground force for circumstances like the above. But as defence is first and foremost that - defence, not attack - I put an even higher priority on those things that we could use should we come under attack.

That means retaining a credible navy, as the sea is our greatest security and we saw in the Falklands how important that was. And we need a well-equipped air-force for similar reasons.

But above all, we need a credible submarine-based nuclear-deterrent, because that is the only thing that any leader of a rogue nation (wherever that may be in future) cannot fool himself that he can take out with a first strike, or survive our retaliation.

It doesn't defend against all threats, for instance terrorist threats, but that is no reason not to defend against the threats that it does deter. The question is not whether we are more likely to be attacked by a terrorist or a rogue state, but whether there is a material risk of each. If we try to defend by balance of probability (one threat is greater than another, so we'll only defend against the first), you can bet that we get attacked by the less probable threat, for the simple reason that we left the door open to it.

There is, of course, some degree of risk that is so small that it is nonsensical to spend much money defending against (e.g. asteroid strike). But it seems to me that it is not at all inconceivable that, in the next thirty years, we could be under threat again from Russia, or from a newly-aggressive China, or from rogue states that we know about now, or which have yet to go completely bad (Pakistan?). But if we can hit a smaller state with a material number of nuclear warheads, or a larger state in cooperation with other nations that were also threatened, I believe they won't regard the thought that we would have difficulty restocking as any reason to want to take the chance on being flattened first time round.

It is sometimes argued that, for the larger potential enemies above, we would have to rely on the Americans anyway, so why waste the money. But I believe we should defend against the smaller states regardless. And America is much more likely to back us up against a major threat if we have taken our share of the cost, and if they were at risk of being dragged in by our action, than if we were toothless.

But above all, this argument is a false economic argument. Our economic problems are immediate. We are facing a deficit of £160bn this year, projected to fall gradually to around £70bn by 2014, but probably accumulating to at least £1,300bn by 2014, of which most of the damage is being done right now. How much will it save us if we scrap Trident or go for a different system? In 2010: nothing. In 2011: nothing. In 2012: you get the drift... Trident has nothing to do with trying to cut our appalling deficits and excessive government spending when we most need to.

If it's a question of going for an alternative, like the LibDems propose, rather than scrapping our nuclear capability altogether, we have no idea if it would be much cheaper, nor whether it would work as well. Some well-informed commentators argue that it may well not be cheaper (http://conservativehome.blogs.com/platform/2010/04/bernard-jenkin-it-is-time-for-some-honesty-from-nick-clegg-on-trident.html).

In any case, there is a terrible lack of scale and perspective in the arguments about whether we can afford Trident. The figures they talk about (upto £80bn) are cumulative spending over 20 years starting in 2015. By contrast, welfare costs us £220bn every year. Healthcare costs us £120bn every year (double, in real terms, what it cost in 1997). Education costs us £80bn every year (up by two-thirds in real terms on 1997).

We are expected to spend £43bn on debt interest this year alone - more than our total defence budget. The cumulative cost of Trident is less than two years' current interest on our national debt. It is very likely that, by the time we have racked up our debts, the interest on them in one year will be more than the total cost of Trident over 20 years. Despite the fact that we have been fighting wars, we have been spending less on defence as a proportion of GDP than at any time since 1900, other than the few years in the 1930s when we were failing to prepare for the Nazi threat (and look how well that worked out for us). See: http://www.ukpublicspending.co.uk/downchart_ukgs.php?year=1900_2011&view=1&expand=&units=p&fy=2010&chart=30-total&bar=1&stack=1&size=m&color=c&title=

We can easily afford to defend ourselves properly if we stop wasting our money on other areas. In my opinion, our focus should be on those other areas, and not on trimming our defence budget or limiting our choice to only British-produced goods.

Perhaps, as a compromise, we could agree that we still have significant capability (comparative advantage) in our dockyards, that aircraft carriers are a vital component of the ability to respond to threats in disparate locations, and that we could therefore achieve your objective and mine by keeping up with the plans to build two aircraft-carriers, which the main parties look very likely to cut back to one or possibly even none. I wonder what would happen if we had a repeat of the Falklands and the Argentines managed to take out our only aircraft carrier? If ever there is a case where having only one unit of something is a critical Single Point Of Failure, surely that is it?