The mission in Afghanistan could "rise or fall," depending on whether the government of Pakistan can stem the flow of insurgents and weapons along its borders, Canada''s defence minister said Saturday.

Speaking at a symposium on the war in Afghanistan, Peter MacKay suggested Pakistan''s border with Afghanistan is like an imaginary line drawn on a map, and that lax security there is a threat to Canadian soldiers.

"We know that Afghanistan at one time was the incubator for terrorism and now it''s Pakistan," he said.

Once inside Afghanistan, Taliban and al Qaida groups are able to "exponentially" influence what''s going on in that country, MacKay said.

Demanding that Pakistan improve its border security is something that Canada and other international forces in Afghanistan are pressing for, he said.

"This issue of free travel between the two countries, the crossings that allow for the transport of weapons and highly motivated terrorists that are coming into the country that are killing Canadian soldiers, international soldiers and Afghan citizens - that''s the concentrated effort we all have to address and we''re all seized with."