The Institute of Strategic Studies estimates that al Qaeda's total strength exceeds 18,000 terrorists. Highlights:
- 2,000 al Qaeda members and more than half of the group's 30 leaders had been killed or captured.
- 1,000 al Qaeda militants estimated to be in Iraq were a minute fraction of its potential strength.
- Al Qaeda is exporting extremism on a global scale with "middle managers" providing planning, logistical advice, material and financing to smaller groups in Saudi Arabia and Morocco and probably Indonesia and Kenya.
- Recruitment is accelerating due to Iraq.
- Al Qaeda's finances are intact.
- The Madrid train bombings in March suggested al Qaeda had now fully reconstituted and had set its sights firmly on the United States and its closest allies in Europe.
NOTE: this estimate may be misunderstood since it is primarily an estimate of the number of people that went through the al Qaeda training camps in Afghanistan, before they were destroyed. Here's a better way to look at this estimate. First, only a small number of people (less than 80, see The Optimal Size of a Terrorist Networks for more) are needed for large-scale attacks. This means that Al Qaeda likely has many more potential recruits (and Afghanistan trained network members) than it is able to utilize.
Second, this estimate may serve as a good way to estimate the number of potential organizers of al Qaeda missions. A percentage, say 25% of the 18,000 (a good model may be the US military's promotion rate), of the Afghanistan trained terrorists serve as the basis for the high flow, highly connected, and very trusted network members that are needed to manage al Qaeda's large attacks (see Mapping Terrorist Networks for more). It would be difficult to develop the connections/trust necessary to manage these attacks from within al Qaeda's network structure without this common bond of face-to-face training.