There are those who are core people to the Al Qaeda organization itself. These are organizers who recruit and oversee local agencies. Maybe about 100 to 600 people at the most.
Then, there are the thousands of fighters who are recruited.
Then, there are the local Al Qaeda affiliates. Some of them were originally created by Al Qaeda, others were local insurgencies who see taking the Al Qaeda name as an advantage. They operate more or less independently from the core organization and would include at least three groups that operate out of Pakistan. This could run into the tens of thousands.
Then, there are local people who agree with the aims of Al Qaeda and may take different amount of activities. Some might take up arms. Others might not want to take up arms, but will provide information for attacks. Others will provide financial support. Some simply will cheer Al Qaeda on. If you include these people, you could run into millions.
Then, there are the people who will work with Al Qaeda if they see it in their benefit, but will switch sides if they’re unhappy with them. This is what happened in Iraq where the Sunnis first supported Al Qaeda because they provided training in attacking the Americans, but later turned away from them when Al Qaeda started attacking them.
So, you can say Al Qaeda has anywhere between 500 to 5,000,000 members depending who you count.
By the way, about 5 years ago, we did find Al Qaeda employee forms, and employee information. This information even included what the employee benefit package includes (vacation, medical coverage, life insurance, etc.) Of course, this probably covers less than a 1000 people. Al Qaeda does also carefully track their funding and who gets it. After all, it is a fairly sophisticated organization at its core.
In Afghanistan, there are probably about 500 to 1000 core Al Qaeda based in Afghanistan, but the Taliban which works very closely with Al Qaeda and the Pakistani security and military agencies may run into 100,000 or more. Plus, you have the Al Qaeda controlled areas in Pakistan which are filled with Pashtun tribes who have family connections with the other Pashtun tribes throughout Afghanistan.
We are in the midst of a civil war in Afghanistan and really shouldn’t be there except that if the Taliban wins, they’ll provide a base for Al Qaeda to operate out of, and they’ll plan attacks on America once again. If the Taliban could be convinced to keep Al Qaeda out of Afghanistan, we’d leave tomorrow morning. We do not want to support a corrupt government that has little support from the population. But, we’re worried about the Taliban allowing Al Qaeda to operate freely in Afghanistan.