The main relevant facts are available in my previous post. You no doubt recall the situation in Iraq in ~2006 or so, at the height of the insurgency; and you no doubt recall the changes that Petraeus made, that changed the situation. And I'm certain that you recall the comments and recommendations for withdrawal and such, that the Democrats were making at the time.
One of the most effective propaganda tools that the insurgents had at the time, was the American tendency toward violent responses that killed civilians as well as terrorists. There, as in Afghanistan, we took care to avoid it -- but the deaths occurred, and the bad guys used them. Petraeus changed the facts on the ground, with great success.
We can certainly acknowledge that Karzai's comments are partly in service of an agenda of his own; but at the same time, he's reminding us of the similarities between the situation in Afghanistan now, and in Iraq at the height of the insurgency.
The situation is tense in Afghanistan, the Taliban are waiting for withdrawal, and they're happy to use civilian deaths to their advantage.
It's a difficult situation -- not something that threats of "immediate withdrawal" will help to solve.