Earlier quoted context omitted.
I really don't think that "Well, Russia's Doing It!" is a very good justification for clearly unethical, and probably illegal, actions. The reason for mass surveillance is control of the populace. Mass surveillance clearly doesn't prevent terrorism: most of this 4th-Amendment-violating dragnet surveillance was in place well before the Boston Bombing, and nobody caught the Tsarnaevs. So, I'm not a little torn, either:…
Do you think it is illegal or unethical for the CIA to just explore these capabilities, or to develop them and use them only in a targeted way, subject to appropriate oversight?
I do not believe that the CIA, as it seems to exist today, is capable of doing that manner of subversion in a targeted way, they have gone rogue. I do not think that the CIA allows itself to be overseen. That part of the question is just not possible to answer.