Read here:

http://www.usvisanews.com/memo2085.html

"The idea that dedicated terrorists would wade through the process of getting permanent resident status in the U.S. or Canada, with all of its delays, security checks, and expense is absurd. All they needed to do was buy forged (or even real) documents for either country and save time and money. I have heard that you can buy green cards in Las Vegas for under $100 - yes, real ones! "