Canadian soldiers joining a team of international peacekeepers in Afghanistan admit the volatility of the war-torn country makes them apprehensive for their mission.

"Terrorism is something that you can't really predict," Master Cpl. John Vanderlinden told CTV's Canada AM before departing CFB Trenton for Kabul.

On the minds of many of the soldiers was a suicide attack that killed four German soldiers in Kabul in June. In all, about 20 NATO-led troops have been killed in attacks by Taliban and al Qaeda holdouts and Afghan warlords.

"A suicide attack -- how can you really defend yourself against the unknown?" said Vanderlinden. "It's a risk we're all going with at the back of our minds."

The 150 Canadian troops that departed for Afghanistan Thursday are part of a 1,800-member Canadian contingent in the International Security Assistance Force, a 29-country mission charged with protecting the fragile interim government of Hamid Karzai and rooting out Taliban, al Qaeda and other resistance forces from Afghanistan.

The troops are joining 350 Canadians already in Afghanistan, and will start patrols August 21.

Canadian Brig.-Gen. Peter J. Devlin is in command of all 3,600 international peacekeepers in Kabul.

Vanderlinden said while he's feeling "apprehensive" about the mission, he believes the Canadian troops are adequately prepared for the challenges they'll encounter.

"The training was excellent and hopefully we'll come back alive," he said.

"I'm not going to take any stupid chances or anything, just do what I was taught and go with my gut feeling."