OTTAWA -- A leading researcher on terrorist travellers says returnees to Canada can be rehabilitated, since those who come back to their home countries are often disillusioned or traumatized.

Others feel they have done their duty to defend Muslim lands and want to lead a more normal life, says Lorne Dawson, a sociology professor at the University of Waterloo and project director for the Canadian Network for Research on Terrorism, Security and Society.

As forces of the Islamic State of Iraq and the Levant scatter, the Liberal government is under pressure to explain what it's doing to contain any threat from foreign fighters returning to Canada.

The Conservatives have peppered the government with questions in the House of Commons about ensuring the safety of Canadians -- accusing the Liberals of welcoming returnees with open arms.

Dawson says simply locking up extremist travellers is not the answer.

"No credible expert in the world thinks you arrest your way out of jihadist radicalization -- it's a social movement," he said Sunday in an interview. "You can't possibly arrest all the people who are engaged with this ideology."

The Canadian Security Intelligence Service has said it is aware of 180 individuals with a nexus to Canada who are suspected of terrorist activity abroad. This could involve front-line fighting, training, logistical support, fundraising or studying at extremist-influenced schools.

Half of these individuals are believed to have travelled to Syria or Iraq.

The intelligence service has also noted a further 60 extremist travellers who have returned to Canada.

But there appears to be scant information about who they are -- and what threat they might pose.

Dawson says his researchers know of about a dozen jihadist returnees to Canada from the Syrian-Iraqi conflict.

"If there's 30, 40 more, we'd be really astounded that we haven't heard something," he said.

"I think there's some kind of confusion going on."

Public Safety Minister Ralph Goodale says the shifting dynamic in Syria and Iraq has the government watching for more extremist-inspired activity on the internet as well as working with allies to track the movements of foreign fighters.

"Where will they go? Will they migrate to Northern Africa? Will they try to get into Europe?" Goodale said during an interview with CTV Question Period broadcast on Sunday.

Prosecuting battlefield returnees to Canada is difficult because there must be evidence that will stand up in court, Goodale said. "And this is an issue that is bedevilling countries around the world in terms of how you actually move from intelligence to evidence, and make a case stick."

He said the chances of turning around someone who has actively engaged in terrorist activities in a war zone were "pretty remote".

Dawson disagrees.

"I think it is possible you could rehabilitate them," he said. "But only with a very careful effort, which we're not well-equipped for in Canada right now."

Dawson's network receives money for research on foreign fighters through a fund administered by the federal Centre for Community Engagement and Prevention of Violence, established by the federal Liberals.

But he believes Canada is playing catchup with other countries when it comes to counter-radicalization efforts.

He points a finger at the previous Conservative government, saying its contribution was limited to providing "minimal funding" for the RCMP's outreach program.

"Everyone in Canada who's informed on these issues, including inside the government, knew full well five years ago we had to be moving in this direction, but the Conservative government refused to do anything."