William Arkin’s Early Warning blog at washingtonpost.com provides the most lucid analysis of the NSA story that I’ve seen so far. The key paragraphs:
In the spring of 2001, NSA began to change direction in its counter-terrorism targeting under Lt. Gen. Hayden: rather than analyzing the mass of what was collected hoping for the gem in the growing mass of available material, NSA began a methodical process of dissecting terrorist target communications practices and network to determine what to collect. This is commonly referred to at NSA as hunting rather than gathering. It was a procedure that was it is infancy on 9/11.
So what happened? The perceived shackles of domestic collection were removed, the gathering process began again to overwhelm the hunting process, new software, data-mining and link analysis methods were applied to isolate potential domestic targets. The beginnings of an era of greater openness and candidness about NSA’s challenges were halted and the agency disappeared into the administration’s secret war.