Milliband is largely correct, if there's not a major shift in tactics. The inedible truth is, that the Karzai Govt is utterly corrupt; is ineffective; has virtually no measureable control outside Kabul; and the Afghan people generally despise him and his Govt.
It's just like 'Nam all over again, where a corrupt, ruthless, out-of-touch puppet Govt., was supported by the Americans - and it was incapable of standing alone without vast amounts of US$'s and political support. All the time, the Yanks fought a ruthless, skilled and determined enemy.
Many of the Afghans are happy with the Taliban system of governing. Vicious, harsh and ruthless as they are; in areas where they have control, they have a form of Govt that is effective in settling disputes; they tax locals with a degree of consultation, and they have support from many locals.
The expert that suggested, a while back, that a coalition with the more moderate elements of the Taliban will be needed to develop effective Govt, and reconstruction in Afghanistan, may have been right. He spoke of a coalition that sidelined the radicals, rather than fight them to a standstill.
Add in large Ethnic divisions (Pashtun, Tajik & Uzbek), that cover language, culture, and long-standing suspicions of the other groups - that prevent unity - and you have a real handful to sort out. It will take a lot of work and a few good leaders with foresight to work out the solution to Afghanistan. I don't see any of those leaders appearing, right at the present moment.
Never forget, that never in the history of the country, has any Western (or Eastern) force won there, with a lasting success. In every case, the "invaders" were repelled, and the Afghan tribes won.
The US-led Coalition and the Campaign Against the Taliban | Singapore Institute of International Affairs