One of the most problematic factors of our current drone program is that it results in blowback terrorism, which is the idea of revenge killings– terrorists commit acts of terror against the United States because of drone strikes. This operates under the same logic of previous terrorist attacks, in which the justification for the attacks were previous US policies. The first Iraq war is an excellent example of this– there were several attacks that were accredited to that intervention.
The most prominent example of this know is Faisal Shahzad, who was incarcerated for committing the Times Square Bombing. He said “I’m going to plead guilty a hundred times over because until the hour the U.S. pulls its forces from Iraq and Afghanistan and stops the drone strikes … we will be attacking the U.S” (my emphasis). This is obviously problematic, because it means that terrorist attacks will continue as long as we continue to do drone strikes.