Dr Paul Cornish
(Former Chatham House Expert)

While the government has begun preparations for next year's strategic defence review the party conference season serves as a reminder that even in the midst of a very demanding commitment to Afghanistan the national defence debate isn't just about military operations; it's also about politics and economics, particularly with a general election in sight. There are growing hints that defence might become the target of Treasury-led panic, and that election-minded politicians, largely inexperienced in military matters, might be tempted by a form of inverse machismo where defence is concerned: 'my cut's bigger than yours'.

The Shadow Chancellor George Osborne appeared to have succumbed recently when he incautiously mentioned several large defence equipment projects - the Typhoon fighter, the Elizabeth-class aircraft carriers and the A-400M transport aircraft - and gave the impression that these projects might come under the Treasury's knife as soon as he takes over. Headline writers pounced: 'MoD budget set to come under fire' (Guardian); 'Tories set to wield axe on £30bn defence projects' (Times). Defence industry was alarmed that complex procurement projects should be dealt with in such an off-hand manner, that Osborne was apparently unaware that such contracts might have break clauses, that a large part of the procurement costs was already sunk, and that some sort of transport aircraft has to be procured in any case.

As the party conference season progresses, it should be asked whether the Treasury - or even the Treasury in waiting - is really the best place from which to approach the national security and defence debate. The armed forces are operationally over-stretched and government spending is under-resourced: a combination which demands careful thinking rather than decision-making by spasm. The MoD has responded in the right way: preparations have begun for the publication early next year of a Green Paper which will inform the defence review. The Conservative defence team has also been thinking hard about the problem and has promised a series of reviews.

This is as it should be. The world shows no sign of becoming a safer and more stable place and money is going to be tight for some time to come. Whichever party is in power next year will have to work hard to match interests, commitments and resources. The first step in the process should be a tour d'horizon of international security. Which national interests matter most? Which risks can be tolerated? This should be a cross-governmental exercise, best conducted by the Cabinet Office rather than the MoD, and should be the reference point for all policy delivery departments. From that first step the MoD should extract the national defence mission and design a force structure best able to meet the most serious and most likely range of security challenges.

So far so good. But then comes the hard part: the country won't have enough money to afford everything. And since that stark fact is already known why not begin the defence review from a position of economic reality and cut a few of the more expensive procurement projects without further ado? To do so would be a disaster for UK security and defence and would repeat the errors of the past. Defence must of course be considered in the context of the health (or otherwise) of the national economy. But international security and national defence cannot be managed as if they were problems for the UK economy alone: not even the Treasury (and not even under Osborne) will be able to pacify and stabilise a volatile world in which the UK is likely to be increasingly involved.

A more intelligent approach to defence is needed, one which takes as its starting point the force structure devised by civilian and military planners as the best way to meet the national defence mission. In times of economic difficulty it is legitimate to ask which aspects of this ideal force structure are most critical to the whole and must therefore be funded as a priority. This is classically the point at which the three armed services go their separate ways and the defence review descends into internecine warfare. But it cannot be unreasonable to expect the three service chiefs - and especially the Chief of the Defence Staff - to come to an agreed inter-service position on the priorities for UK defence. Thereafter, it should be possible to decide where defence risks must be taken and to identify those parts of the structure which can be kept in suspended animation, to be resuscitated when the economy picks up again. Some capabilities might be superfluous, to be cut altogether, and it might be that some functions could be achieved more efficiently by other government departments.

The key point is that defence is an idea or a principle which must of course be modified by the availability of resources. But defence should not - and need not - be a desert camouflaged expression of the parlous state of the national economy.

Paul Cornish is the Carrington Professor of International Security at Chatham House and is the co-author with Andrew Dorman of 'National Defence in the Age of Austerity', International Affairs, July 2009.