U.S. Senator John McCain says military exit dates and exit strategies in Afghanistan should not even be discussed until NATO gets the upper hand in its fight against Taliban militants.

U.S. Senator John McCain fields a reporter's question as Rick Hillier, former chief of Canada's defence staff, looks on after a session on Afghanistan at the Halifax International Security Forum in Halifax. (Andrew Vaughan/Canadian Press)

McCain told the Halifax International Security Forum on Saturday that "success" in the war-torn country is the way out of the conflict.

"The exit strategy is success," he said. "It's when you succeed and start to draw down."

He also said history shows that if a withdrawal date is set, "the enemy waits until you leave."

Retired Canadian general Rick Hillier, meanwhile, told the forum that the West has "one shot" to turn the war around in the next 12 to 18 months.

"The surge, in my view, is fundamental here," he said. "It's absolutely essential."

Hillier and McCain spoke one day after Ottawa began to cement its 2011 withdrawal plans.

Defence Minister Peter MacKay said he has been talking with other countries, including the U.S., about providing security for Canadian diplomats and aid workers whose mission will continue after the army comes home.

Gen. Stanley McChrystal, commander of U.S. forces in Afghanistan, put in a request two months ago for an additional 40,000 troops. Currently, there are 68,000 U.S. troops in Afghanistan.

McCain, who lost his U.S. presidential bid last year, told reporters on Friday that President Barack Obama's delay in reaching a decision on Afghan strategy is creating uncertainty within the military as the situation in Afghanistan continues to worsen.

In television interviews last week, Obama talked about seeking an "end game" with his new Afghanistan policy, and said his administration doesn't want an "open-ended" strategy.

A clear, articulate vision is essential if NATO is to turn things around within the next 18 months, and Obama is the one to deliver it, Hillier said.

"I think that ability could influence a lot of populations outside of the United States of America, including people in Canada and western Europe," said the general, who retired as Canada's chief of defence staff last year.

About 300 delegates, including the defence ministers from Canada and the U.S., are attending the forum to discuss everything from the future of NATO to the war in Afghanistan.

Outside the conference, 100 protesters held a demonstration earlier in the afternoon.

With files from The Canadian Press