With the war in Afghanistan grinding towards its ninth anniversary, talk in some quarters is turning to a deal between Western states and the Taliban. But how might that work?
Taliban leaders handing over top al-Qaeda members? Mullah Omar, as international statesmen, welcomed in the West?
It all sounds far-fetched. But these are the sorts of theories being batted between some well informed observers of Nato's war in Afghanistan.
With British military casualties in Afghanistan numbering 275, and more than 1,000 US fatalities so far, talk in some quarters is turning to a negotiated settlement.
Former UN envoy Kai Eide has confirmed in a BBC interview he held secret talks with the Taliban last year - though such contacts, he added, were disrupted by the arrests of leading Taliban figures by the Pakistani authorities.
And in a speech earlier this month British Foreign Secretary David Miliband said, while violence had begun the Afghan conflict, "politics will bring it to an end".
But how would Britain and the US get a deal with an enemy not only opposed to their occupation of its land, but also diametrically at odds with many of its values? As Mr Miliband acknowledged, "political engagement with those who would directly or indirectly engage our troops is difficult. We have no right to betray our values".
If a deal is to be done, what would it need to involve?
1. BUYING OFF FOOT-SOLDIERS
For some time, the US and its allies have been talking about reintegrating lower-ranking insurgents into civilian life, offering payments and employment as encouragement. The assumption here is that many who fight for the Taliban are not as ideologically motivated as the leadership.
Tired of fighting, maybe, but is he ready to do a deal?
How do we know? Felix Kuehn, one of very few Westerners living in the Taliban stronghold of Kandahar, says some of the insurgents are "unemployed young people for whom it is probably something to do at the weekend". Others, such as Ahmed Rashid, an expert on the Taliban, believe simply a lot of the Afghan Taliban are "very tired", with older generations engaged in 30 years of fighting and their families often in exile.
However, purely financial persuasion won't work, says Michael Semple, who maintained good contacts with the Taliban while working for the EU in Afghanistan. Many insurgents will want to try and show that they have retained a "mantle of rectitude" in their long battle.
And there's a further potential twist. If the more pragmatic Taliban give up their fight, including the older generations who have been fighting the longest, that may give more influence to younger, more ideological leaders who come from the madrassas - Islamic schools - in Pakistan.
2. FOREIGN TROOPS OUT
If the West were to strike a deal, a key condition for the Taliban would be the removal of foreign troops. The Taliban talks proudly of having formed its group fighting Soviet invaders in the 1980s, just as its ancestors defied the British Empire.
But its not just hardliners who resent the foreign presence, believes Thomas Ruttig, a former diplomat and UN official with long experience of Afghanistan. "A lot of people just feel uneasy about troops kicking in their doors and driving like hell through the streets," he says.
From Nato's perspective, withdrawal has political appeal - with member states coming under pressure because of the cost of the fighting. When US President Barack Obama announced a surge in troop numbers last year, he simultaneously gave a date for drawing the numbers down.
But timing here is crucial.
The Taliban wants troops out as a precondition for peace talks. Western leaders, however, want to be able to say they are handing over security to a broadly-based Afghan government, with its army and police forces, not insurgents and local warlords.
3. TURN IN BIN LADEN
How did this all start? The US and its allies invaded Afghanistan in response to 9/11, as the Taliban regime had given shelter to al-Qaeda and its leader, Osama Bin Laden.
So the permanent breaking of the relationship between the Taliban and al-Qaeda would be a key Western demand.
Could the Taliban turn in Bin Laden?
Michael Semple says there are those in the Taliban who see its ties with the terror group as a "relationship of convenience they realise they have to extricate themselves from al-Qaeda".
But how to make that break explicit? By the Taliban turning, in Western eyes, from poacher to gamekeeper, says Ahmed Rashid.
"One of the only ways [the Taliban] could actively demonstrate it would be to go after al-Qaeda themselves," says Mr Rashid, who has watched this relationship from its beginning. "[T]he Taliban leaders know more about the whereabouts of Bin Laden and other such leaders of al-Qaeda then perhaps anyone else".
The Taliban helping the West end its long hunt for Bin Laden is a fascinating challenge to the political imagination. But, adds Mr Rashid, it's "an enormously big step for the Taliban to take and we don't even know if that's going to be possible".
4. PROTECTING WOMEN'S RIGHTS
Progress on women's rights could be undone
When the Taliban ruled Afghanistan, most women's roles were highly restricted and education was denied to many girls. There have been hard won changes since. But the thought of turning back the clock to those days is the source of some of the greatest anxiety about any deal between the West and the Taliban.
US Secretary of State Hillary Clinton would want women's rights to be at the centre of any negotiation.
But there's a fear that any deal would allow the Taliban to impose its rules on parts of the country where it has remained highly influential in local society.
But from his vantage point living in Kandahar, Felix Kuehn sees room for compromise.
"What we hear these days a lot is actually the local Taliban commanders rolling back a couple of the very, very strict rules they had in the past concerning you know beards, music and television and all these kinds of things".
5. NO HUMILIATION
Everyone agrees a deal must be found that does not humiliate one side or the other.
"If it were to look like defeat," says Michael Semple, "it wouldn't work."
Taliban who did a deal, he believes, would want to feel they could remain "honoured members in society", even if they did not enjoy the control they had before their regime was overthrown in 2001.
Could Mullah Omar get the Gaddafi treatment - shunned then welcome?
Other players in Afghanistan and in the wider region would also need to feel they had been part of the deal too - notably Pakistan, which has heavily influenced the Afghan Taliban, but also other watchful neighbours such as India and Iran.
Any negotiation is likely to be long, unpredictable and divisive, with a substantial group within the Taliban opposed to compromise.
But although it may be hard to imagine political agreement emerging from such bitter conflict, a longer historical perspective suggests such a deal may well be how the conflict ends.
Professor Malcolm Chalmers, former British government adviser on Afghanistan, reminds us that "there are not a few examples of British colonial history where the people we are fighting one year, five or 10 years later ended up being the president with whom we had cordial diplomatic relations"
So could a President Mullah Omar one day arrive in Britain on a state visit? A bitter prospect for those who have lost relatives in the current conflict. And still, many would say, highly unlikely.
But if politics moves up the agenda while the fighting is seen as less decisive, some very surprising things could happen.
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