There are two ways to view this: 1. By letting them know how we collect intelligence, they will find ways to evade us. 2. By letting Americans know that we ar

There are two ways to view this: 1. By letting them know how we collect intelligence, they will find ways to evade us. 2. By letting Americans know that we are spying on them, we risk a backlash and possible budget cuts. I suspect that both of these were going through the heads of high-ranking decision makers at the NSA (and the FBI and the DEA).