As far as I know, there's no requirement that you be a U.S. citizen. In fact, I just looked on their signup page, and there is a blank to fill in your country, but no blank to fill in your citizenship.
A gunfight is not the time to learn new skills.
If you ever have a real need for more than a couple of magazines, your problem is not a shortage of magazines. It's a shortage of people on your side of the argument. -- Art Eatman