Can the Taliban ever be trusted to keep their side of the bargain?

Every time I read the latest statement from the Taliban spokesman, one Zabihullah Mujahid, on the state of play with the peace deal negotiations in Qatar between the insurgents and the US negotiating team, I get the same chilling feeling down my spine. They, the Taliban, seem pretty pleased with the way it's all going. "Long and useful" were the words the spokesman chose to describe the meeting that has just finished. Well you could say that tells us nothing. But the Taliban wouldn't use the word "useful" unless the talks were inching their way towards the sort of deal which they want. All we are allowed to know so far is that the withdrawal of US troops from Afghanistan, and presumably the coalition troops too, is being offered in return for a Taliban promise not to let terrorists have safe sanctuary in the country. That quid pro quo is meaningless. The Taliban can promise until the cows come home but there is no way they, on their own, can keep out Isis and al-Qaeda. In fact it's not their job to kick Isis and al-Qaeda out of Afghanistan. That's the job of the Afghan government with, at the moment, the massive heLp of the 5,000 American counter-terrorist forces and strike aircraft. So the only thing the Taliban actually has to promise is that they won't support either Isis or al-Qaeda, or give them training areas or provide them with arms. Well first of all the Taliban hate Isis anyway, so there's no way they are going to give them sanctuary. And as for al-Qaeda, the Taliban can easily say to the US negotiators: "Look, we're not going to let them live amongst us, provided we know who they are, and we'll give them no assistance. Promise, cross my heart and hope to die. So, in return please withdraw all your 14,000 troops." Is that really going to be the deal? There has got to be a helluva lot more to the "long and useful" talks than that to convince me that peace at last in Afghanistan is a peace at last that benefits every man, woman and child in Afghanistan.