Ambassadors are supposed to be diplomatic. But, by all accounts, there was nothing particularly sensitive about the opinions outlined in the leaked memo from the American Ambassador to Afghanistan, Karl Eikenberry. In the note to the White House, Mr Eikenberry is said to have articulated grave concerns about Hamid Karzai's government and argued against sending more US troops to the country.
As a former military commander in Afghanistan, Mr Eikenberry's opinion will have particular weight in Washington. And this dramatic intervention clearly represents another serious challenge to the case, made by the US commander General Stanley McChrystal, for a further 40,000 US troops to be dispatched to Afghanistan.
Yet a danger lies in an exclusive focus on the issue of troop reinforcements. Still more important is the need for an overhaul of the Western strategy in the country, which is plainly foundering. Any dreams of turning Afghanistan into a model democracy need to be set aside. Any opportunity to build a new nation was lost when the US and others turned away from the country in the direction of Iraq after the toppling of the Taliban in 2001. The objective now must be to stabilise Afghanistan with a view to withdrawing Western troops in the medium term. If more boots on the ground can help to achieve this – as General McChrystal argues they would – there remains a strong case for sending them. And Western leaders must be clear with their domestic publics that stabilisation is now their collective "war aim".
But the future of this mission will not simply hinge on the number of troops. What matters is how these forces are used. There are two tasks which they need to prioritise. The first is to protect the Afghan population from Taliban attacks. The second is to build up the Afghan state's capacity to take care of its own security.
No one disputes that the Afghan police are, at present, woefully inadequate. And confidence in them has been severely dented by the killing of five British soldiers by an Afghan policeman last week. Yet there is no alternative to training up the Afghan security forces. A sudden pullout of Western forces is not a realistic prospect. A gradual transfer of authority is the only feasible exit strategy. The sooner the day arrives that foreign forces are able to entrust security duties to Afghan forces, the sooner they will be able to withdraw.
Reform of governance is the other crucial piece in this jigsaw. President Karzai might be no more corrupt than a host of other leaders in the region, but those leaders are not being propped up by 100,000 Nato troops. If our forces come to be regarded as protectors of a rapacious regime in Kabul, this stabilisation mission will not succeed.
It has been suggested that Barack Obama is delaying his decision on reinforcements to put pressure on President Karzai to sack corrupt ministers and officials. If so, such an approach makes sense. The West will never have a pristine partner in Kabul; but it must have a vaguely credible one.
President Obama is ultimately right to demand that the strategy for stabilising Afghanistan must be clear (and a realistic troop exit scenario laid out) before more troops can be committed. And the US President is also right to argue that it remains far from clear whether such a strategy is yet in place.