Here is information from the Federal Register dates January 26, 2012. Note the penalties. If you are a permanent resident of Canada who has not become a Canadian citizen …
http://www.gpo.gov/fdsys/pkg/FR-2012-01-26/html/2012-1567.htm
[Federal Register Volume 77, Number 17 (Thursday, January 26, 2012)] [Proposed Rules] [Pages 3964-3966] From the Federal Register Online via the Government Printing Office [www.gpo.gov] [FR Doc No: 2012-1567]