[ZenGum]

IMHO Afghanistan cannot be secured unless the Northwest Territory Tribal Area of Pakistan is brought under effective control. As it is the Pakistani government does not and cannot control it, nor will they allow foreign forces to take control there (else they lose their claim to it); thus leaving it as a permanent safe-haven for baddies.

My preferrred option is for Pakistan to cede all areas it cannot control and maybe join them on to Afghanistan. I don't see that happening, though, governments and nations do not just give up territory, no matter how troublesome it is.

Of course, this is only one necessary condition for a stable Afghanistan. There are many more.