The September 11 terrorist attacks have led to a rapid tightening of security at the Canada-U.S. border. The attacks demonstrate the need for specific measures to overcome terrorist groups' challenge to North America as a whole. The paper claims that current Canada-U.S. shared projects are insufficient, and creation of a perimeter around both countries will require standardization of policies in several areas. The challenge is to do so without compromising Canadian sovereignty. The paper argues that a multi-layered response would go a long way toward meeting the challenge of international terrorism. Combining effective national laws, policies, and practices with carefully crafted and implemented transnational or cross-border mechanisms would meet transnational threats "on their own turf" and help shore up Canadian and U.S. positions on this increasingly sophisticated menace. Notes