President Obama: "We might have caught him some other way. We might have disrupted it because a New York cop saw he was suspicious. Maybe he turned out to be incompetent and the bomb didn't go off. But, at the margins, we are increasing our chances of preventing a catastrophe like that through these programs."
http://sitrep.globalsecurity.org/articles/130619909-did-the-nsa-foil-the-zazi-pero.htm