He'll acknowledge the truth now that what he says no longer matters
Confronted directly by a RT reporter he could no longer deny it. Starts at 2:20:

So not only did rebels keep civilians hostage but so did specifically the US-linked rebels, or else there wouldn't be a need for US to tell them to knock it off. - If indeed US ever did such a thing as Kerry claims.
For half a year now US officials have insisted civilians in the eastern Aleppo pocket fear and loathe the Syrian government and would never wish to come under its control. -- So perhaps the hostage situation suited Kerry far more than a civilian exodus.
In any case when the Syrian army took over most of the pocket this month civilians very jubilant that the worst of the war was now over for them.
That Kerry has now somewhat improved his rhetoric is 'nice' but we should note he has only done it now that what he says or thinks no longer carries any weight.
Since the breakdown of the Kerry-Lavrov deal, Trump election win and Syrian advances in Aleppo he has been reduced to an observer and a commentator without influence on events which are being driven by Russia and Damascus instead.
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