Micah Zenko, Douglas Dillon Fellow
"Signature strikes"—attacks based on patterns of activity—were first authorized by President George W. Bush in 2008 for CIA drone strikes against suspected militants in Pakistan. As reported by David Sanger in his book The Inheritance: The World Obama Confronts and the Challenges to American Power, the threshold for who could be killed was lowered in 2008 from "high-value targets" (HVTs) or "personality strikes," to what was termed the "reasonable man" standard. Subsequent reporting by Jo Becker and Scott Shane in the New York Times revealed that the Obama administration continued the policy whereby a signature strike "in effect counts all military-age males in a strike zone as combatants." The Obama administration has also expanded this practice for targeted killings in Yemen in 2012.
The Obama administration has repeatedly refused to acknowledge that it conducts signature strikes, or to explain how the killing of anonymous military-aged males based on their observable behavior meets the principle of distinction in the law of armed conflict (the idea of distinction is to only engage valid military targets). Before President Obama's recent counterterrorism speech, it was reported that the United States was going to either scale back or end signature strikes. However, the president never discussed implementing these options, and when his senior aides were asked about them in a background briefing prior to the speech, they too were unresponsive.
Subsequently, there is no evidence that signature strikes will be reduced or ended based upon anything the Obama administration has recently stated.