After a dozen or so 'Human Shields' are killed along with the Taliban, they'll see its a useless tactic and stop. But as long as we hold fire they'll continue to use them.
Or, to be humane -- have more Marine Scout-Sniper Teams in the field. They can put a round in a Taliban's skull without any problem or injury to the 'shield'. Seeing this the Taliban would also stop using 'human shields'.
Killing civilians isn’t the answer, leave that to the Taliban. Snipers are the answer and I’m sure they are getting quite a workout.