Holder testified about this under oath in response to adversarial questioning from Senator Cruz and was clear that without an imminent threat that would endanger America (this was stated several different ways, all under oath) the US couldn't use lethal force of any sort on a terrorist on American soil. The example used was of an al Qaeda terrorist sitting at a cafe; a "cafe strike".

Holder said not only would lethal force be inappropriate (he actually started by saying "with the facts you've provided we wouldn't even be able to arrest the person"), but that the Constitution would not permit the Administration to use it.