THE SHEER MAGNITUDE of the foiled plot that British authorities announced yesterday was breathtaking. This may well have been “the next big one” that experts have predicted al Qaeda would attempt. As Friday began, British authorities had apprehended 24 suspects alleged to be part of a plot to blow up as many as 10 transatlantic flights with liquid explosives. As a result, some widely-held assumptions among terror analysts may now come crashing down.

One assumption that took root in recent years is that al Qaeda’s central leadership is isolated and incapable of calling the shots for terror attacks of any significant magnitude. In truth, there was good reason to doubt this assumption even before the transatlantic air plot was announced.