Although this site comes in for some (unfair) abuse from Sunny Hundal at times, it is worth pointing out that he has a written an article which I suspect all contributors to this site would broadly agree with.
If the Taliban succeed in re-establishing themselves, then they would also be the base for further terrorism aimed at India, Pakistan, the US and UK. We’d have to come back sooner or later.
Lefties opposed to the conflict in Afghanistan must confront two things: that conditions in the subcontinent were much more unstable before the US invasion of 2001 and will get worse if the US leaves with Afghanistan in limbo. That may mean even more lives lost. Second, sometimes we need a short-term conflict (between the Pakistani army and the Taliban) in order for longer-term peace.
Without going too much into the history of how Afghanistan was created – and the involvement of western powers during the Soviet Invasion – this mess is partly our fault. To give up now won’t make things any better for anyone. Staying, however, may improve the region – given the right strategy. For me that remains the preferable option.