War is not the place for on-the-job training. That is the opinion of Des Browne, the Defence Secretary, and, doubtless, most if not all of Britain's most senior military commanders. Yet the size of the Army and the scale of the international commitments that Britain has taken on mean that soldiers are often being sent into the field with insufficient fighting skills. Although Mr Browne does not put it so bluntly, the implication of his remarks is that these men in uniform risk being killed or injured as a result.

That is unacceptable. There are only two ways in which the position could be resolved. Either more troops must be found (by new recruitment or redeployment or, realistically, both sources) or the next prime minister must make a conscious decision to reduce the British presence in parts of the world where it exists today and resist calls to take part in future international operations. The notion that Britain can simply muddle through, stretching an army that consists of fewer than 96,000 personnel across a variety of conflicts and continents, is not credible. Major decisions will have to be taken once Tony Blair has stood down and many of these options will require more money.

In the short term, some redeployment should be possible. The size of the functioning Army has fallen from 156,500 in 1990 to 112,000 in 1997, when this Government assumed office, to 95,560 now. There remain about 9,000 soldiers based in Northern Ireland and it is hoped that, subject to political progress, this number could be almost halved by the summer. If the Iraqi Army reaches a sufficient standard, the 7,000 British troops in and around Basra could be halved in about the same timeframe. Mr Browne also makes it plain that he regards the continued presence of more than 600 British soldiers in Bosnia performing the duties of policemen as "inappropriate". So, in theory, 8,000 troops could become available.

It would be very unwise, nevertheless, simply to assume that matters in Ulster or Iraq will proceed smoothly in the course of the coming six months or that other countries will volunteer to replace British forces stuck in Bosnia or that no other crisis will erupt. If, as seems to be the case, there is a consensus that Britain should play a major part in international war and peace, then the fully trained strength of the Army needs to be up to 10,000 larger than it currently is. That process of increasing the size of the force should start with the replacement of four infantry battalions (about 2,400 personnel) axed in 2004.

In the medium term, however, ministers have to consider a fundamental shift in the balance of spending between the services. All the available evidence indicates that the demands on the British military overseas are likely to fall on to land-based operations, with the Army shouldering the vast majority of the burden and the Royal Navy and the Royal Air Force undertaking significant but ultimately secondary and supporting roles. Defence procurement has to reflect that reality. The notion that each Service in entitled to a minimum distribution of the spoils is unsustainable.

The military has long protested that the Treasury, under the command of Gordon Brown, has little love for it and regards its budget as an item of expenditure to be restrained so as to allow for social spending to increase. If Mr Brown wants to maintain that approach as Prime Minister, the only honest course for him to take is to declare early on in his tenure that he will resist overseas engagements. If not, then he has to be the ultimate poacher turned gamekeeper for the Army.