The killings were part of a broader program of "targeted killing" by the United States outside the context of armed conflict and based on vague legal standards, a closed executive process, and evidence never presented to the courts.
This entire statement is absurd. It assumes that there was no nexus in a military target and the defense of the United States, and that the proper process must require the military and its chain of command to get court approval for attacking a target outside the borders of the United States. The courts will not make this decision. They will wisely and consistent with the Feres doctrine not have the courts second guessing military operations. The solution is going to require an act of congress which implements safeguards against these foreign military operations which have American casualties. The discussion is good, and putting in safeguards is appropriate, and those safeguards may involve judicial review at some point in the process, but the courts have consistently and continually declined jurisdiction for such interventions which supersede the Constitutional balance of power.