Seems drone kills have recently been put on the list of international war crimes.
So Obama's speech might be a reaction to this
http://www.globalresearch.ca/the-leg...-crime/5334665
and that
http://www.cbsnews.com/8301-18563_16...drone-strikes/
"Oops well you know our drone attacks killed a lot of civilians, but we will be more cautious in the future."