The border guards that stopped Ahmed Ressam aka "The Millennium Bomber" were American border guards at Port Angeles, WA.
Ressam had crossed into the U.S. on the Victoria, B.C.- Port Angeles, WA ferry and U.S. Customs officer Diana Dean gets the credit for flushing him out.
U.S. Customs officer Diana Dean told the Digest she found the olive-skinned Canadian who identified himself as "Benni Norris" unusually nervous. The ferry from Vancouver had just chugged up to its slip at Port Angeles, Washington on the afternoon of December 14, 1999, and Norris lowered the window of his Chrysler 300. Despite the chilly air, he was sweating, Dean noticed. When she asked him to open his trunk, he bolted. After a brief chase, "Norris"/Ressam was arrested. In the trunk, they found 130 pounds of plastic explosives, two 22 ounce plastic bottles full of nitro glycol, and a map of LAX. (The link is incorrect about Vancouver. The ferries at Port Angeles have a Port Angeles-Victoria run.)
The only Canadian role in that case was the fact that Canada had made Ahmed Ressam a landed immigrant of Canada.
Many of the folks around here are more worried about the little brown lettuce picker.