In Foreign Affairs The Business Habits of Highly Effective Terrorists There's a direct relation between the level of bureaucracy and things like cell size and security. Terrorist will often trade down on security for greater operational efficiency. Spectacular ops usually aren't very secure. I read 9-11 involved over 70 guys operating on foreign turf, leaving lots of trail behind them, really rather impracticable but it took the towers down. Similarly intell agencies can be crippled by over compartmentalization and extreme secrecy but if they err to far in the other direction in order to do the job they can be exposed as in the Snowdon affair. The article gets rather critical of Dr al-Zawahiri of AQ for his leaky communications that seems to have led to the recent mass closure of US diplomatics posts. He might think that a bit of loose talk was rather more parsimonious way of nipping at the Far Enemy than actually bothering with blowing anything up.