Why it is 'over to the Afghans' with UK troop reduction
UK Prime Minister David Cameron's statement to the House of Commons has set the course for a gentle run down of British troops in Helmand.
About 500 will go, which when added to the 450 or so freed up by shifting certain air operations from Kandahar will mean the overall total of British troops declines from around 10,000 to about 9,000 by the end of next year.
Anyone who has walked the fields or streets of Afghanistan with British troops will know that there is an enormous amount still to be done.
The business of trying to foster professionalism in local security forces or government officials seems as tangled, and as immune to Western-imposed deadlines, as ever.
Standing to give his statement the prime minister was though able to roll out some good arguments that things are getting better:
Whereas three years ago three quarters of terrorist plots in the UK were said to have originated in the Afghanistan/Pakistan border area, "I am advised that this figure is significantly reduced", he said; he noted that Afghan forces would reach targets of 171,000 Afghan National Army (ANA), and 134,000 police by the end of October; and the death of Osama bin Laden, Mr Cameron argued, "present the Taliban with a moment of real choice".
Some of the assertions he made could easily be criticised, and others may offer hostages to fortune, but in the light of the general air of scepticism or war weariness that seems to prevail on both sides of the Atlantic now it is worth looking at the possible grounds for optimism.
In the first place, the build up of Afghan security forces is a significant factor. It is perhaps the most important single feature of the Obama administration's big investment in the war.
The argument about quality, and the failings of the Afghan army can continue endlessly, particularly if one pays too much attention to the often scornful assessment of the British or American rank and file.
But the fact is that when British troops were committed to Helmand in 2006, the total number of Afghan soldiers and police in the field across Afghanistan was fewer than 50,000.
The growth in Afghan numbers has allowed the ANA to be built up in some previous insurgent hotbeds, after Nato forces cleared them. The insurgents' freedom of action in districts like Arghandab or Panjway in Kandahar province or Marjah and Nad e Ali in Helmand has been considerably reduced.
What will happen as Nato forces pull back? Afghan forces will come unstuck here and there, but the overall level of violence may well fall. When the Soviet army left, the mujahideen collapsed in many areas because locals simply lacked the will to fight fellow Afghans.
Security forces on the scale planned for Afghanistan - anything up to 400,000 - simply cannot be sustained by that country. If Mr Cameron's declarations about the long term nature of Britain's commitment are to be honoured, the West will have to continue paying the bills for this security establishment for many years to come.
The killing of Bin Laden also puts a positive tick on the balance sheet. It makes it harder to argue that all US efforts in the region have come to nothing and shows a continued ability to eliminate someone who inspired global militancy.
It would be fanciful to think that the loss of Bin Laden will cause the Taliban to throw in the towel. But it may add to the sense of war weariness, and the need for political dialogue, that Nato and its Afghan allies also feel. This is why the prime minister and others are talking up the dialogue process, and chances for a broader political settlement with the insurgents.
Of course there are all manner of threats to progress too. The Af/Pak equation is so complex that success in one quarter often generates an adverse response in another.
Pakistan's retaliation for the Bin Laden operation in limiting CIA operations in their country may, intelligence officials fear, ease the pressure on the jihadist leadership.
When one looks at the billions that have disappeared in corruption, it is also worth questioning how much security has really been bought with the fielding of so many new Afghan army battalions.
However there are those, even in the senior ranks of the military who believe that the surge has achieved its purpose of checking what seemed like unstoppable insurgent momentum in the south, and that now it really is a matter of "over to the Afghans".
That is the context for the prime minister's statement and this first, cautious, reduction, in British troops.