Even If Edward Snowden's leaks have caused irreparable harm to national security, those of us without security clearances only have the government's word to take for it. But this week's disclosure that a specific conference call between al Qaeda leaders was detected and recorded by the National Security Agency is precisely the sort of information that should not be in the public domain until the threat has passed, precisely the sort of secret that almost no one has a problem with the government keeping.
If it's true that al Qaeda leaders change their communication tactics to find a way around the NSA dragnet, they sure as hell are going to avoid the same circuits that somehow tapped this conference call. They're going to do it before the immediate threat has passed, too, meaning that the NSA will lose a real-time source of intelligence that might have provided further information about the target of the planned attack. Initially, several news outlets reported simply that the U.S. had detected "chatter" about an attack. Then, McClatchy added some detail, reporting the names of several al Qaeda leaders, including Nasser al-Wuhayshi, who participated in the discussion. Then, Eli Lake reported that the discussions had taken place on a specific conference call. (See Marcy Wheeler's timeline for more.)
The number of people who would be cleared to possess the level of detail that identified a particular conference call as the relevant SIGINT activity is tiny. It is one thing to say broadly that U.S. officials overheard "discussions," because someone planning an attack probably discusses it in some way many times. Even then, though, you could imagine a mad scramble by jihadists for new communication safe zones.
There are two reasons why the government would tolerate this type of leak. One: The threat was so severe that the only way to prevent it was to expose the plot completely, showing al Qaeda that the U.S. had penetrated so deeply into their organization that the big boss's double-top-secret conference call was recorded. It's the counter-terrorism equivalent of face up poker. There's an element of brinksmanship in this approach.
Two: The U.S. intelligence community might want al Qaeda to shift its communication methods because the new method al Qaeda ends up with might be more intercept-friendly in the future, or the U.S. believes that certain al Qaeda members it keeps under constant surveillance will help them quickly figure out the new method.
Note that several early articles referred to the (Yemeni) interception of a courier, which might — might — mean that the U.S. got its hands on a copy of the tape and does NOT have al Qaeda pinned to the wall. IF the U.S knew where the conference call took place, they ostensibly have a very good bead on Ayman al-Zawahiri's head, too.
Or, the leaks could be completely unauthorized.
If another big, bad leak investigation is soon, ah, leaked, then we'll know. Until then, let's just say that something doesn't look quite right.