They estimated 20,000 al Qaeda terrorists were trained in Afghanistan before we went to Afghanistan and rooted out the Taliban. They claim to have killed 2,000 al Qaeda since that time. The 18,000 figure is an estimate, not a hard count. There is no accounting or estimate for how many new al Qaeda have been recruited since we entered Afghanistan. In short, the numbers are unsupported by facts. It sure makes for flashy headlines.
Thanks, I missed it the first tome I read it.