John O. Brennan said this quote

Unfortunately, in war, there are casualties, including among the civilian population.

~ John O. Brennan

I will not, nor will I ever, publicly divulge sensitive intelligence sources and methods. For when that happens, our national security is endangered and lives can be lost.

~ John O. Brennan

I do not - I never believed it's better to kill a terrorist than to detain him. We want to detain as many terrorists as possible so we can elicit the intelligence from them in the appropriate manner so that we can disrupt follow-on terrorist attacks.

~ John O. Brennan

The actions that we take on the counterterrorism front, again, are to take actions against individuals where we believe that the intelligence base is so strong and the nature of the threat is so grave and serious, as well as imminent, that we have no recourse except to take this action that may involve a lethal strike.

~ John O. Brennan