A former top official on Canada's work in Afghanistan is warning against getting too involved in Iraq without clear and realistic objectives.

David Mulroney, who served as the deputy minister in charge of the Afghanistan Task Force, said Canada hasn't looked closely enough at its experience in Afghanistan.

"When I recently saw Foreign Minister [Rob] Nicholson musing that we'd apply some of the lessons of Afghanistan to our engagement, I kind of sat bolt upright because I think one of the problems is we haven't spent much time learning the lessons of Afghanistan," Mulroney said in an interview to air Saturday at 9 a.m. on CBC Radio's The House.

Mulroney said a newly released audit shows "how hard it was to get that development assistance and humanitarian assistance right in a place where none of the officials were really clear about what Canada's objectives were."

Mulroney also served as secretary to the Independent Panel on Canada's Future Role in Afghanistan, which was led by former foreign affairs minister John Manley, and as foreign and defence policy adviser to the prime minister.

He said the lack of discussion about Afghanistan toward the end of the 10-year mission has kept Canadians from learning key lessons, which include being realistic about how much Canada doesn't know about a region and setting "often very modest" goals.

Mulroney also said Canada needs an exit strategy.

"When does it happen for us and who's around to pick up the pieces of what we've put in place. Until we've really talked honestly about that, I'd be very worried about our ability to pull something off in a place that's as challenging as that nexus of Iraq and Syria."

He also warned the government has to think about how the humanitarian, military and diplomatic pieces fit together.

"If it's being done now, this is the time to tell Canadians that people have thought about that. Because if it hasn't been done, we'll get the same ultimately disappointing results that audit points to on Afghanistan."

Resuming duties

Mulroney made the comments as the military held what is likely its last briefing on the Iraq mission before the House considers a motion to extend and expand the six-month Canadian Armed Forces operation.

Canadian Forces spokesman Capt. Paul Forget told journalists at Friday's briefing that two special forces colleagues of Sgt. Andrew Doiron, who was killed two weeks ago in a friendly fire incident, are gradually resuming their duties in Iraq,

Sgt. Andrew Doiron was killed in a friendly fire incident in Iraq. It was the first Canadian death during the ongoing anti-ISIS mission. A third colleague is in stable condition in Canada and receiving medical care, Forget said.

The team of special forces operators was returning to an observation post at night in northern Iraq when the Kurdish allies fired on them, killing Doiron and injuring the three others. An investigation into the incident is afoot, Forget said.

Forget said the Canadian Forces have conducted 417 air sorties and 53 strikes in support of the international coalition waging war against the Islamic State of Iraq and Syria, known as ISIS.

Earlier this week, Prime Minister Stephen Harper said the government intends to "move forward with a request for Parliament for extension and expansion of the mission."

He wouldn't say whether that could include the possibility of going into Syria as well.

The current mission is set to expire on April 7.

Coalition can strike in Syria

The original mission was limited to Iraq, with Harper clearly telling MPs that the Canadian military would only operate where it had "the clear support of the government of that country." That ruled out missions in Syria, despite it being part of the ISIS base of operations.

But with Harper referring to an expansion of the mission, and Defence Minister Jason Kenney talking about ISIS regrouping across the Syrian border from Iraq, Forget faced a number of questions about a possible geographic expansion.

Canadian Forces spokesman Capt. Paul Forget says the military's Iraq operation has conducted 417 air sorties and 53 strikes in support of the international coalition waging war against ISIS. (CBC News) ​"Although Canada is limited to operations in Iraq as per the mandate provided to us by the government, the coalition overall has contributing nations that are able to strike in Syria," Forget said.

"So the movement of that equipment [by ISIS]... can still be prosecuted, targeted, by the coalition, just by another nation within the coalition at this time."

Last week, Kenney told CBC Radio's The House that Canada was watching the movement "with great interest."

"We do note with interest that ISI[S] is moving much of their armoured equipment back into Syria. They appear to be consolidating in and around their ersatz capital of Raqqa in east-central Syria."

Vote not legally required

Although the prime minister has made it a hallmark of his government to give MPs the opportunity to debate and vote on proposed military missions, parliamentary consent is not actually required to deploy Canadian troops. That authority rests exclusively with the executive, which excises it on behalf of the Crown.

In an essay published last fall, University of Ottawa professor and defence expert Philippe Lagassé noted that such votes can be seen as a "courtesy" extended to MPs by the executive.

"The votes allow MPs to express themselves on a matter of national importance," he pointed out.

"In addition, they can be seen as a means of assuring the military that their mission has the support of the elected house of Parliament, and the votes add an aura of democratic legitimacy to controversial policy decisions."

But it can also provide political cover for the governing party, he adds.

"By laundering these decisions through the House, the government gives the impression that the Commons shares responsibility for the deployment."