Canada is well-known among terrorists around the world as one of the easiest countries to enter undetected, says Alan Bell, president of Globe Risk Holdings, an international security consulting firm based in Toronto.

The Immigration Department is understaffed and thus unable to thoroughly background every potential immigrant and refugee, Bell says. Moreover, the naturalization process is so long that it often takes years to complete.
During that time, Bell said, terrorists simply stop reporting to immigration officials and disappear.

"Then they're free and easy, they're in Canada, and they can do what the hell they like," Bell says. "Once a bad guy has dropped out of the immigration system or the refugee system, the chances of picking this guy up are very slim, unless they do something very stupid or wrong.
     
"So you've effectively got someone who's in the country, who's not being monitored, and after a year or two he starts doing what he was originally sent here to do in the first place, which is either collect financing for a terrorist organization in his home country; act as a halfway house; do training and operational planning; or become a mule for terrorist groups to move equipment and weapons and manpower in and out of the U.S."