A few points.
1. The Taliban put the Haqqani Network, which was allied with Al Qaeda, in charge of security in Kabul and was running security at the airport
2. The head of ISIS-K is a former Haqqani network commander
3. Afghan officials said that the Haqqani network and ISIS-K are the same
4. Whether or not that’s true, units from the Taliban have joined ISIS-K.
5. The Taliban are an umbrella group. Their level of organization is debatable. Making deals with them is meaningless. You make deals with individual commanders.
6. Jihadi groups are like gangs. Their commanders shift alignment. Their loyalties are unclear.
In Syria, we saw FSA units we were funding that were actually operating with Al Qaeda and ISIS. These are not militaries in our sense, they’re opportunistic and contextual.
7. There is no such thing as operational security when your security arrangement includes terrorists.
That’s true in Kabul, it was true in Benghazi, Tunis, etc
Even if you have a deal with a terrorist leader, the Jihadis you’re working with right now still hate you
8. The Taliban fight ISIS-K for their own reasons because they’re rivals. But it doesn’t mean that elements of the Taliban can’t and won’t team up with ISIS-K. Or that some Jihadi units may be both the Taliban and ISIS-K.
Jihadi battlefields allow for that kind of flexibility
9. You can’t negotiate with terrorists.
Trying will backfire in a number of ways because even if the terrorist leaders don’t stab you in the back, their people will.
The United States keeps making the mistake of treating Jihadist groups like representatives of some legitimate government. Even aside from the fact that they are our sworn enemies, it’s like assuming that you can stop gang violence in Chicago by meeting with a top gang leader.
Politicians have tried it. It doesn’t work.
That’s because gangs do what they’re going to do. And their leaders can guide them to do what they want to do already, but getting them to do what they don’t want to do quickly reveals the limits of their power.
Jihadis want to kill, kidnap, rape, and go about their usual business. If you ask them to do those things, it works pretty well. But getting them to stop doing those things quickly shows the illusion of any kind of leadership.
That’s how Al Qaeda lost the crown to ISIS. It’s why ISIS-K made inroads among the Taliban.
Terrorist leaders look strong and effective when they unleash violence. They quickly lose their authority when they try to restrain the Jihad. (There’s plenty of unfortunate parallels to contemporary American politics here.) Negotiating with them about turning their violence on a particular target can be reasonably effective if they already want to take on that target. Take the Mujahadeen and the USSR, for example.
But asking them to restrain from carrying out attacks against Americans is a mostly futile task. What will happen, as it does in Gaza and the West Bank, and in a dozen other conflicts, is that the leaders will disavow responsibility and give the all-clear for an attack anyway.