Read a book by "Omar Nisiri" (nome de plume) called "Inside the Jihad". In it he describes his experience at the various AQ training camps in Afghanistan prior to 9/11. See chapters 6-8. Many of the attendees were from western Europe (England, France, Germany, Belgium, Holland), and probably a few from America too. Once they attended between 4 and 12 months of continuous training, they returned to their homes to serve in a sleeper role.

In Iraq, our forces encountered a few of the Chechens who had attended the camps. Chris Kyle's book describes one such encounter. This also explains why the Chechens were able to put up such an effective resistance in Chechnya, but also later in Iraq.

I believe that many of the leaders in the Sunni resistance groups during the "Arab Spring," Syrian civil war, and now ISIS/ISIL are men who attended these camps. This also means that we already have these guys here in the states, regardless as to the status of our borders.

On equipment: You get what you inspect, not what you expect.
On training: Our drills are bloodless battles so that our battles are bloody drills.
On tactics: Cheating just means you're serious about winning.