The NSA can't even keep it a secret that they are spying on people, or how, and they are *SUPPOSED* to spy on people. How do you think the government (multiple governments now), the media and academia could have all covered this up when one spy agency can't hide it's activities.(Snowden thought it was unconstitutional to spy on US citizens, how many people would need to not have a problem with sacrificin US lives for a 'war on terror' - when that doesn't make sense - or a war in Iraq, which proved to be bogus)
Now perhaps you subscribe to the notion that the US government is almost all powerful and could do almost anything! In which case i must refer you to two examples, one the bay of pigs invasion - a disaster of action on the part of the US spy agencies (CIA?) but also a brilliant example of the limits of their capabilities. And second, the massively siccessful evacuation of US citizens from Iran, after the Iranian revolution. These smart citizens hide in the Canadian embassy, and the Canadians agree to conspire to produce fake passports for them - so the CIA snuck into Iran on fake passports, went to the Canadian embassy, carefully trained these Americans to speak with Canadian accents and came up with a cover story (of being a tv/film crew or similar) and the walked out and took a flight home!
That is real spy stuff which was a massive success for the CIA. Also it isn't all that impressive a story. Not particularily sexy or exciting... Barely even made it into a film. But it is an example of the real ability of the CIA (with the cooperation of the Canadian government, because hey, why forge documents when you can ask an ally to make them...)
This does not fill me with courage for their ability to pull off a massive false flag operartion, killing thousands without anyone leaking anything for over ten years.