If you can accept a laundry list of times in the past where we know our government has overthrown sovereign governments by planting fake 'rebels', introduced agent provocateurs to give the illusion that a group is radical, attacked civilian targets and blamed the enemy, introduced chemical agents on innocent populations, sank our own ships and killed our own people to start a war, etc etc
You see, with these NSA stories, how our government reacts to whistle blowers, its tendency to label everyone and everything terrorist, and a litany of bald faced lies, all credibility and good will this government may have had has been tossed out the window.
How did we get here? Plausible deniability. All our government has to do is make sure there is little to no proof of their activities until years after the fact to keep the operation going. Since there is no proof immediately available, people argue that since there is no proof then it's not a valid argument. Yet, when the evidence is uncovered years later these same people will ignore the evidence of past behavior thinking "well, that was in the past under administration X".
I submit that a pattern of past behavior is evidence of present activity. Sure, my conclusions may be wrong, but given how little faith we have in our own government, is it any surprise that such accusations are asserted?
Remember the Maine!