Canada's spy service is warning of an increasing threat from "home-grown terrorists" already living in communities across the country.
Canadian Security Intelligence Service (CSIS) deputy director of operations Jack Hooper made the comments Monday before a Senate defence committee.
He says young Canadians from immigrant backgrounds are becoming radicalized through the internet and are looking for targets at home, not abroad.
"They are virtually indistinguishable from other youth. They blend in very well to our society, they speak our language and they appear to be — to all intents and purposes — well-assimilated," he said.
"[They] look to Canada to execute their targeting."
The men responsible for the 2005 transit bombings in London were from immigrant families, said Hooper.
"I can tell you that all of the circumstances that led to the London transit bombings, to take one example, are resident here now in Canada," he said.
Training camps in Afghanistan produce terrorists, said Hooper, including a Canadian resident who played a key role in an earlier attack.
"The individual who trained the bombers in the August 1998 attack on the U.S. Embassy in Nairobi was a former resident of Vancouver who fought in Afghanistan," he said.
That is a good reason for Canadian troops to remain in Afghanistan, he said.
Hooper, who complained about cuts in funding, says it is difficult to properly screen immigrant applicants.
Of the roughly 20,000 from the Pakistani-Afghanistan region, Hooper said CSIS could only vet about "one-tenth."
The Senate committee is looking into Canada's mission in Afghanistan, which has recently been extended two years until 2009. About 2,300 soldiers are currently deployed in the country.