Leading article: The fiscal tail wags the military dog

David Cameron began his Commons statement unveiling the Strategic Defence Review yesterday with the emphatic declaration that: "This is not simply a cost-saving exercise". But the Prime Minister protested too much. And that assertion was, in any case, contradicted by the number of times Mr Cameron went on to blame the dire financial legacy of the previous Labour government for closing down options. The Prime Minister cannot have it both ways.

In fairness, there are some necessary reforms in this defence review. The overhaul of hardware procurement is needed after the staggering inefficiency and mismanagement of this budget by the previous government. And the Trident decision will be put off until next Parliament. This is welcome – and, it is to be hoped, a prelude to the scrapping of the grotesquely expensive and impractical nuclear deterrent altogether. The Liberal Democrats have not been crowing about this victory, but the decision will enable them to go into the next election in full-throated opposition to Trident.

The withdrawal of British troops from Germany is also clearly overdue, as is the decommissioning of the tanks designed to counter the Soviet Union during the Cold War. The suggestions that these cuts will leave Britain militarily vulnerable are unconvincing. While Britain's aircraft carriers will not be able to host jets until 2019, helicopters and pilotless drones will still be able to take-off from them.

Yet in the final analysis, this exercise has clearly been driven by cost-cutting, rather than proper strategic analysis, just as the Defence Secretary, Liam Fox, complained in his leaked letter to the Prime Minister earlier last month. The glaring example is the decision to proceed with the construction of two new aircraft carriers while cutting the number of frigates. The Coalition gives the distinct impression that, in a perfect world, it would have scrapped these carriers. And most senior officers (outside the Navy at least) have not been keen on them. But according to Mr Cameron, the decision was made to proceed because it would have been more expensive to cancel the construction projects than to continue.

Yet this is surely the financial tail wagging the defence dog. Britain might, or might not, need two aircraft carriers in the future (and there is a serious argument that these enormous floating weapons platforms are actually extremely vulnerable to enemy attack). But the decision should be made based on a considered analysis of Britain's future defence needs, rather than the cost of exiting contracts.

Personnel in the three services are to be cut in more or less equal numbers, which suggests a salami-slicing approach, rather than considered strategic choices. There seems to have been little consideration given to radical options such as merging the different forces.

And this all flows from the Coalition's ill-judged determination to eradicate the entire deficit over the course of a single parliament. This offence was compounded by the Treasury's insistence that the Defence Review be completed in time to coincide with the Comprehensive Spending Review. The whole exercise has been packed into five months. The last defence review, in 1998, ran for more than double that time.

The previous Government did leave the Ministry of Defence in a mess, with troops overstretched in Afghanistan and gross overspending on hardware. But in attempting to undo those mistakes over such a short period, the Coalition is at real risk of creating a mess of its own. Yesterday we saw how national investment in defence will be distorted by this needlessly draconian timetable. Today, when the Chancellor unveils the Comprehensive Spending Review, we will see the rest of the damage.