Leading article: A modest contribution to keep the top brass at bay

But the big decisions are still being hammered out in Washington

The Prime Minister's announcement that another 500 troops are to be sent to Afghanistan has all the hallmarks of a holding operation. But it also suggests continuing concern among the top brass about present manning levels in the field and a desire on the part of the Government to start off on the right footing with the new Chief of the General Staff, General Sir David Richards.

More boots on the ground has been a recurring theme of military representations for a year now, even if the specific complaint by the former Chief of the General Staff, Sir Richard Dannatt, that his request for another 2,000 troops was turned down, may be less clear-cut than it appears. But one of the reasons for the refusal – if refusal it was – may lie in the caveats with which Gordon Brown hedged the new commitment yesterday. The 500 troops, he said, would be dispatched only if the requisite equipment was available; if other Nato allies increased their troop numbers and if more Afghan troops were trained.

The first condition can be seen largely as presentational, for the benefit of military and public opinion. How well the troops are equipped for combat, and how well protected they are against the lethal threat of improvised explosive devices, remains a public preoccupation – even if, as ministers insist, such concerns are out of date. The requirement that other Nato allies increase their contribution also looks largely designed for domestic opinion, while upping the pressure on others to contribute a little more.

But these conditions, like the third – that more Afghan troops must be trained – also smack a little of buck-passing. The Prime Minister does not want to be held responsible for dispatching troops who are not properly equipped, so it is up to the top brass to ensure that they are. This proposed increase in British troops should not excuse others from doing their bit; so the French and Germans (by implication) are invited to increase their troop numbers correspondingly. And the matter of Afghan troops looks like a way of encouraging the Afghans to do more.

So there still seems some uncertainty about whether the additional 500 will actually be sent. Even if they are, however, it has to be asked how much difference they will make. The number constitutes an increase of barely more than 5 per cent on the 9,000 already serving in Afghanistan. They may help to relieve the pressure on the new brigade that has just taken over in Helmand Province. But it will not make the difference between overall victory and defeat.

The truth is that Britain, and the other Nato forces, are waiting on President Obama. Until he decides what course the US is going to take, everything is essentially on hold. Care has to be taken not to lose ground against the Taliban, but also to do nothing that would prejudice any of the options under consideration. The discussion, to the extent that it has become public, has been wide-ranging: from an Iraq-style "surge" requiring thousands more troops, to a slimmed-down operation narrowly focused on preventing the re-establishment of terrorist bases.

With the Afghan election results still not finalised and fierce disagreement in Washington about how far President Karzai should be supported, Mr Obama has made known he needs more time. Britain's extra 500 troops amount to a modest statement of the UK Government's continued commitment – to the operation and to the well-being of the troops already in the field. That is welcome, but it offers no clue to what might come next.